Device and method for forming a lesion

ABSTRACT

The invention provides surgical systems and methods for ablating heart tissue within the interior and/or exterior of the heart. A plurality of probes is provided with each probe configured for introduction into the chest for engaging the heart. Each probe includes an elongated shaft having an elongated ablating surface of a predetermined shape. The elongated shaft and the elongated ablating surface of each probe are configured to ablate a portion of the heart. A sealing device affixed to the heart tissue forms a hemostatic seal between the probe and the penetration in the heart to inhibit blood loss therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of co-pending application Ser.No. 08/943,683, which is a continuation-in-part of commonly-assigned,co-pending application Ser. No. 08/735,036 filed Oct. 22, 1996; which isa continuation-in-part of application Ser. No. 08/425,179, filed Apr.20, 1995; which is a continuation-in-part of U.S. Pat. No. 5,571,215,issued Nov. 5, 1996; which is a continuation-in-part of U.S. Pat. No.5,452,733, issued Sep. 26, 1995. The complete disclosures of theseapplications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] It is well documented that atrial fibrillation, either alone oras a consequence of other cardiac disease, continues to persist as themost common cardiac arrhythmia. According to recent estimates, more thanone million people in the U.S. suffer from this common arrhythmia,roughly 0.15% to 1.0% of the population. Moreover, the prevalence ofthis cardiac disease increases with age, affecting nearly 8% to 17% ofthose over 60 years of age.

[0003] Although atrial fibrillation may occur alone, this arrhythmiaoften associates with numerous cardiovascular conditions, includingcongestive heart failure, hypertensive cardiovascular disease,myocardial infarcation, rheumatic heart disease and stroke. Regardless,three separate detrimental sequelae result: (1) a change in theventricular response, including the onset of an irregular ventricularrhythm and an increase in ventricular rate; (2) detrimental hemodynamicconsequences resulting from loss of atroventricular synchrony, decreasedventricular filling time, and possible atrioventricular valveregurgitation; and (3) an increased likelihood of sustaining athromboembolic event because of loss of effective contraction and atrialstasis of blood in the left atrium.

[0004] Atrial arrythmia may be treated using several methods.Pharmacological treatment of atrial fibrillation, for example, isinitially the preferred approach, first to maintain normal sinus rhythm,or secondly to decrease the ventricular response rate. While thesemedications may reduce the risk of thrombus collecting in the atrialappendages if the atrial fibrillation can be converted to sinus rhythm,this form of treatment is not always effective. Patients with continuedatrial fibrillation and only ventricular rate control continue to sufferfrom irregular heartbeats and from the effects of impaired hemodynamicsdue to the lack of normal sequential atrioventricular contractions, aswell as continue to face a significant risk of thromboembolism.

[0005] Other forms of treatment include chemical cardioversion to normalsinus rhythm, electrical cardioversion, and RF catheter ablation ofselected areas determined by mapping. In the more recent past, othersurgical procedures have been developed for atrial fibrillation,including left atrial isolation, transvenous catheter or cryosurgicalablation of His bundle, and the Corridor procedure, which haveeffectively eliminated irregular ventricular rhythm. However, theseprocedures have for the most part failed to restore normal cardiachemodynamics, or alleviate the patient's vulnerability tothromboembolism because the atria are allowed to continue to fibrillate.Accordingly, a more effective surgical treatment was required to curemedically refractory atrial fibrillation of the heart.

[0006] On the basis of electrophysiologic mapping of the atria andidentification of macroreentrant circuits, a surgical approach wasdeveloped which effectively creates an electrical maze in the atrium(i.e., the MAZE procedure) and precludes the ability of the atria tofibrillate. Briefly, in the procedure commonly referred to as the MAZEIII procedure, strategic atrial incisions are performed to preventatrial reentry and allow sinus impulses to activate the entire atrialmyocardium, thereby preserving atrial transport functionpostoperatively. Since atrial fibrillation is characterized by thepresence of multiple macroreentrant circuits that are fleeting in natureand can occur anywhere in the atria, it is prudent to interrupt all ofthe potential pathways for atrial macroreentrant circuits. Thesecircuits, incidentally, have been identified by intraoperative mappingboth experimentally and clinically in patients.

[0007] Generally, this procedure includes the excision of both atrialappendages, and the electrical isolation of the pulmonary veins.Further, strategically placed atrial incisions not only interrupt theconduction routes of the most common reentrant circuits, but they alsodirect the sinus impulse from the sinoatrial node to theatrioventricular node along a specified route. In essence, the entireatrial myocardium, with the exception of the atrial appendages and thepulmonary veins, is electrically activated by providing for multipleblind alleys off the main conduction route between the sinoatrial nodeto the atrioventricular node. Atrial transport function is thuspreserved postoperatively, as generally set forth in the series ofarticles: Cox, Schuessler, Boineau, Canavan, Cain, Lindsay, Stone,Smith, Corr, Chang, and D'Agostino, Jr., The Surgical Treatment ofAtrial Fibrillation (pts. 1-4), 101 Thorac Cardiovasc Surg., 402-426,569-592 (1991).

[0008] While this MAZE III procedure has proven effective in ablatingmedically refractory atrial fibrillation and associated detrimentalsequelae, this operational procedure is traumatic to the patient sincesubstantial incisions are introduced into the interior chambers of theheart. Moreover, using current techniques, many of these proceduresrequire a gross thoracotomy, usually in the form of a median stemotomy,to gain access into the patient's thoracic cavity. A saw or othercutting instrument is used to cut the sternum longitudinally, allowingtwo opposing halves of the anterior or ventral portion of the rib cageto be spread apart. A large opening into the thoracic cavity is thuscreated, through which the surgical team may directly visualize andoperate upon the heart for the MAZE III procedure. Such a large openingfurther enables manipulation of surgical instruments and/or removal ofexcised heart tissue since the surgeon can position his or her handswithin the thoracic cavity in close proximity to the exterior of theheart. The patient is then placed on cardiopulmonary bypass to maintainperipheral circulation of oxygenated blood.

[0009] Not only is the MAZE m procedure itself traumatic to the patient,but the postoperative pain and extensive recovery time due to theconventional thoracotomy substantially increase trauma and furtherextend hospital stays. Moreover, such invasive, open-chest proceduressignificantly increase the risk of complications and the pain associatedwith sternal incisions. While heart surgery produces beneficial resultsfor many patients, numerous others who might benefit from such surgeryare unable or unwilling to undergo the trauma and risks of currenttechniques.

SUMMARY OF THE INVENTION

[0010] Accordingly, it is an object of the present invention to providea surgical procedure and system for closed-chest, closed heart ablationof heart tissue.

[0011] It is another object of the present invention to provide asurgical procedure and system for ablating medically refractory atrialfibrillation.

[0012] Yet another object of the present invention is to provide asurgical procedure and surgical devices which are capable ofstrategically ablating heart tissue from the interior chambers orexternal cardiac surfaces thereof without substantially disturbing thestructural integrity of the atria.

[0013] Still another object of the present invention is to enablesurgeons to ablate medically refractory atrial fibrillation while theheart is still beating.

[0014] In accordance with the foregoing objects of the invention, thepresent invention provides surgical systems and methods for ablatingheart tissue within the interior and/or exterior of the heart. Thisprocedure is particularly suitable for surgeries such as the MAZE IIIprocedure developed to treat medically refractory atrial fibrillationsince the need for substantial, elongated, transmural incisions of theheart walls are eliminated. Moreover, this technique is preferablyperformed without having to open the chest cavity via a mediansternotomy or major thoracotomy. The system is configured for beingintroduced through a small intercostal, percutaneous penetration into abody cavity and engaging the heart wall through purse-string incisions.As a result, the procedure of the present invention reduces potentialpostoperative complications, recovery time and hospital stays.

[0015] A system for transmurally ablating heart tissue is providedincluding an ablating probe having an elongated shaft positionablethrough the chest wall and into a transmural penetration extendingthrough a muscular wall of the heart and into a chamber thereof. Theshaft includes an elongated ablating surface for ablating heart tissue.The system of the present invention further includes a sealing devicefixable to the heart tissue around the transmural penetration forforming a hemostatic seal around the probe to inhibit blood losstherethrough.

[0016] A preferred method and device for ablating the heart tissue iswith a cryosurgical ablation device. Although cryosurgical ablation is apreferred method, a number of other ablation methods could be usedinstead of cryoablation. Among these tissue ablation means are RadioFrequency (RF), ultrasound, microwave, laser, heat, localized deliveryof chemical or biological agents and light-activated agents to name afew.

[0017] More specifically, the system of the present invention enablesthe formation of a series of strategically positioned and shapedelongated, transmural lesions which cooperate with one another toreconstruct a main electrical conduction route between the sinoatrialnode to the atrioventricular node. Atrial transport function is thuspreserved postoperatively for the treatment of atrial fibrillation.

[0018] The system includes a plurality of surgical probes each having anelongated shaft. Each shaft includes an elongated ablating surface of apredetermined shape for contact with at least one specific surface ofthe heart and specifically the interior walls of atria chamber. Suchcontact with the ablating surface for a sufficient period of time causestransmural ablation of the wall. Collectively, a series of strategicallypositioned and shaped elongated, transmural lesions are formed whichcooperate with one another to treat atrial fibrillation. Each transmuralpenetration includes a purse-string suture formed in the heart tissuearound the respective transmural penetration in a manner forming ahemostatic seal between the respective probe and the respectivetransmural penetration to inhibit blood loss therethrough.

[0019] When using a cryosurgical probe, the probe includes a shafthaving a delivery passageway for delivery of pressurized cryogentherethrough and an exhaust passageway for exhaust of expended cryogen.The pressurized cryogen is expanded in a boiler chamber thereby coolingthe elongated ablating surface for cryogenic cooling of the elongatedablating surface. The elongated shaft is configured to pass through thechest wall and through a penetration in the patient's heart for ablativecontact with a selected portion of the heart.

[0020] In another aspect of the present invention, a surgical method forablating heart tissue from the interior and/or exterior walls of theheart is provided including the steps of forming a penetration through amuscular wall of the heart into an interior chamber thereof andpositioning an elongated ablating device having an elongated ablatingsurface through the penetration. The method further includes the stepsof forming a hemostatic seal between the device and the heart wallpenetration to inhibit blood loss through the penetration and contactingthe elongated ablating surface of the ablating device with a firstselected portion of an interior and/or exterior surface of the muscularwall for ablation thereof.

[0021] More preferably, a method for ablating medically refractoryatrial fibrillation of the heart is provided comprising the steps offorming a penetration through the heart and into a chamber thereofpositioning an elongated ablating devices having an elongated ablatingsurface through the penetration and forming a hemostatic seal betweenthe ablating device and the penetration to inhibit blood losstherethrough. The present invention method further includes the steps ofstrategically contacting the elongated ablating surface of the ablatingdevice with a portion of the muscular wall for transmural ablationthereof to form at least one elongated transmural lesion and repeatingthese steps for each remaining lesion. Each transmural lesion is formedthrough contact with the ablating surface of one of the plurality ofablating device and the strategically positioned elongated transmurallesions cooperate to guide the electrical pulse pathway along apredetermined path for the surgical treatment of atrial fibrillation.

[0022] The entire procedure is preferably performed through a series ofonly five purse-strings sutures strategically located in the right andleft atria, and pulmonary vein portions. Generally, multiple lesions canbe formed through a single purse-string either through the use ofassorted uniquely shaped ablating devices or through the manipulation ofa single ablating device.

[0023] It should be understood that while the invention is described inthe context of thoracoscopic surgery on the heart, the systems andmethods disclosed herein are equally useful to ablate other types oftissue structures and in other types of surgery such as laparoscopy andpelviscopy.

[0024] The procedure and system of the present invention have otherobjects of advantages which will be readily apparent from the followingdescription of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is an upper left, posterior perspective view of a humanheart incorporating the system and procedure for treatment of medicallyrefractory atrial fibrillation constructed in accordance with theprinciples of the present invention.

[0026]FIG. 2 is a right, antero-lateral perspective view of the humanheart incorporating the present invention system and procedure thereof.

[0027]FIGS. 3A and 3B are schematic diagrams of the atria portion of theheart illustrating the pattern of transmural cryolesions to create apredetermined conduction path in the atrium using the system andprocedure of the present invention.

[0028]FIG. 4 is a top plan view of a set of cryoprobe devicesconstructed in accordance with the present invention, and utilized inthe system and procedure of the present invention.

[0029]FIG. 5 is a top perspective view of a patient showing use of thesystem and procedure on the patient.

[0030]FIG. 6 is an enlarged, fragmentary, top plan view, incross-section, of one of the cryoprobes in the set of cryoprobes of FIG.4, illustrating the expansion chamber thereof.

[0031] FIGS. 6A-6D illustrate use of a slidable insulative tube forinsulating portions of the probe.

[0032]FIG. 7 is a front elevation view, in cross-section, of theablating end of a cryoprobe, taken substantially along the plane of theline 7-7 in FIG. 6.

[0033]FIG. 8 is a front elevation view, in cross-section, of analternative embodiment of the ablating end of FIG. 7.

[0034]FIG. 9 is a transverse cross-sectional view of the system andpatient, taken through the patient's thorax generally along the plane ofthe line 9-9 in FIG. 11A, showing the relative positioning of the rightand left intercostal percutaneous penetrations.

[0035]FIG. 10 is a front schematic view of a patient's cardiovascularsystem illustrating the positioning of a cardiopulmonary bypass systemfor arresting the heart and establishing cardiopulmonary bypass inaccordance with the principles of the present invention.

[0036] FIGS. 11A-11D is a series of top plan views of the patientundergoing a pericardiotomy as well as the installation of apurse-string suture and a stay suture to assist in suspending thepericardium.

[0037] FIGS. 12A-12C is a series of enlarged, fragmentary side elevationviews looking into the patient's thoracic cavity at the right atriumthrough a soft tissue retractor (not shown) in the system of FIG. 5, andillustrating the introduction of cryoprobes constructed in accordancewith the present invention through purse-strings for the formation of aposterior longitudinal right atrial cryolesion and a tricuspid valveannulus cryolesion.

[0038]FIG. 13 is an enlarged, fragmentary, transverse cross-sectionalview, partially broken away, of the system and patient's heart of FIG.5, and illustrating the introduction of a tricuspid valve cryoprobethrough a purse-string suture in the right atrial freewall to form theelongated, transmural, tricuspid valve annulus cryolesion.

[0039]FIG. 14 is a side elevation view peering at the right atrialappendage through the soft tissue retractor passageway (not shown) inthe system of FIG. 5, showing the formation of a perpendicular rightatrial cryolesion.

[0040]FIG. 15 is a fragmentary, transverse cross-sectional view of thesystem and patient's heart, illustrating the formation of a right atrialanteromedial counter cryolesion.

[0041]FIG. 16 is an upper left, posterior perspective view the humanheart of FIG. 1, illustrating the location of the purse-string suturesin the right and left atrial walls, to access opposite sides of theatrial septum wall for the introduction of an atrial septum clampingcryoprobe.

[0042]FIG. 17 is a fragmentary, transverse cross-sectional view,partially broken away, of the system and patient's heart, showing theatrial septum clamping cryoprobe engaged with the atrial septum wall forthe formation of an anterior limbus of the fossa ovalis cryolesion.

[0043]FIGS. 18A and 18B is a sequence of enlarged, fragmentary,transverse cross-sectional views, partially broken away, of the systemand patient's heart, illustrating the technique employed to enableinsertion of the distal ends of the atrial septum clamping cryoprobethrough the adjacent purse-string sutures.

[0044] FIGS. 19A-19D is a series of fragmentary, transversecross-sectional views, partially broken away, of the system andpatient's heart, showing the formation of an endocardial pulmonary veinisolation cryolesion using a four-step process.

[0045]FIGS. 20A and 20B is a sequence of fragmentary, transversecross-sectional views, partially broken away, of the system andpatient's heart, showing the formation of the pulmonary vein isolationcryolesion through an alternative two-step process.

[0046]FIG. 21 is an upper left, posterior perspective view of the humanheart illustrating the formation of an additional epicardial pulmonaryvein isolation cryolesion.

[0047]FIG. 22 is a fragmentary, transverse cross-sectional view of thesystem and patient's heart, showing the formation of a left atrialanteromedial cryolesion.

[0048]FIG. 23 is a fragmentary, transverse cross-sectional view of thesystem and patient's heart, illustrating the formation of a posteriorvertical left atrial cryolesion.

[0049]FIG. 24 is a top plan view of the right angle cryoprobe of FIGS.12A and 12B.

[0050]FIG. 25 is a top plan view of the tricuspid valve annuluscryoprobe of FIG. 13.

[0051]FIG. 26 is a top plan view of an alternative embodiment of thetricuspid valve annulus cryoprobe of FIG. 25.

[0052]FIG. 27 is a top plan view of the right atrium counter lesioncryoprobe of FIG. 15.

[0053]FIG. 28 is a top plan view of the atrial septum clamping cryoprobeof FIGS. 17 and 18.

[0054]FIG. 29 is an enlarged front elevation view, in cross-section, ofa coupling device of the septum clamping cryoprobe, taken substantiallyalong the plane of the line 29-29 in FIG. 28.

[0055]FIG. 30 is an enlarged rear elevation view, in cross-section, ofan aligning device of the septum clamping cryoprobe, taken substantiallyalong the plane of the line 30-30 in FIG. 28.

[0056]FIG. 31 is an enlarged, fragmentary, top plan view of analternative embodiment to the atrial septum clamping cryoprobe of FIG.28.

[0057]FIG. 32 is a top plan view of an all-purpose cryoprobe of FIGS.19A and 19B.

[0058]FIG. 33 is a top plan view of the pulmonary vein loop cryoprobe ofFIGS. 20 and 21.

[0059]FIG. 34 is a top plan view of the left atrial anteromedicalcryoprobe of FIG. 22.

[0060]FIG. 35 is a top plan view of an alternative embodiment of theall-purpose cryoprobe of FIG. 23.

[0061]FIG. 36 is an enlarged, fragmentary, top plan view of analternative embodiment to the cryoprobes formed for contact of theablation surface with the epicardial surface of the heart.

[0062]FIG. 37 is an exploded view of a cryogen delivery tube.

[0063]FIG. 38 is a partial cross-sectional view of the probe having thedelivery tube of FIG. 37.

[0064]FIG. 39 is an exploded view of the outer tube of the probe of FIG.38.

[0065]FIG. 40 is an end view of the ablating surface of the probe ofFIG. 39.

[0066]FIG. 41 shows a probe having a delivery tube with adjustable holeswherein an outer tube is slidably movable relative to an inner tube.

[0067]FIG. 42 shows the probe of FIG. 41 with the outer tube moveddistally relative to the inner tube.

[0068]FIG. 43 shows a probe having vacuum ports for adhering the probeto the tissue to be ablated.

[0069]FIG. 44 is a cross-sectional view of the probe of FIG. 43 alongline I-I.

[0070]FIG. 45 shows a probe having a malleable shaft.

[0071]FIG. 46 shows the tip of the probe of FIG. 45.

[0072]FIG. 47 is a cross-sectional view of the probe of FIG. 45 alongline II-II.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0073] Attention is now directed to FIGS. 1-3 where a human heart H isillustrated incorporating a series of strategically positionedtransmural lesions throughout the right atrium RA and the left atrium LAformed with the heart treatment procedure and system of the presentinvention. FIG. 1 represents the desired pattern of lesions created onthe right atrium RA, including the posterior longitudinal right atriallesion 50, the tricuspid valve annulus lesion valve annulus lesion 51,the pulmonary vein isolation lesion vein isolation lesion 52 and theperpendicular lesion 53; while FIG. 2 represents a right, anteriorperspective view of the heart H illustrating right atrium RA including aright atrial anteromedial counter lesion 55. The cumulative pattern oflesions reconstruct a main electrical conduction route between thesinoatrial node to the atrioventricular node to postoperatively preserveatrial transport function. Unlike prior surgical treatments, the systemand procedure of the present invention, generally designated 56 in FIGS.4 and 5, employ a closed-heart technique which eliminates the need forgross multiple elongated incisions of the atria to ablate heart tissuein the manner sufficient to preclude electrical conduction of reentrantpathways in the atria.

[0074] In accordance with the heart treatment procedure and system ofthe present invention, a set of uniquely-shaped, elongated tip ablationprobes 57 (FIG. 4, to be discussed in detail below) are employed whichare formed and dimensioned for insertion through at least one of aplurality of heart wall penetrations, preferably sealed by means ofpurse-string sutures 58, 60, 61, 62 and 63, strategically positionedabout the atria of the heart H. Once the distal end of the probe isinserted through the desired purse-string suture, an elongated ablatingsurface 65 thereof is maneuvered into contact with the selectedendocardial surface of an interior wall of the atria to create anelongated, transmural lesion. As shown in FIGS. 3A and 3B, theseindividual lesions collectively form a pattern of transmurally ablatedheart tissue to surgically treat medically refractory atrialfibrillation.

[0075] Briefly, FIG. 4 represents a collection or set of probes 57constructed in accordance with the present invention which are employedto preclude electrical conduction of reentrant pathways in the atriausing closed-heart surgical techniques. Collectively, as will beapparent, the probes enable the surgical formation of a series oflesions which are illustrated in FIGS. 3A and 3B. Each probe (FIGS.24-28 and 32-35) includes an elongated shaft 66 formed to extend throughan access port or passageway 67 in a retractor 68 (FIG. 5) which ismounted in a percutaneous intercostal penetration. The terms“percutaneous intercostal penetration” and “intercostal penetration” asused herein refer to a penetration, in the form or a cut, incision,hole, retractor, cannula, trocar sleeve, or the like, through the chestwall between two adjacent ribs wherein the patient's rib cage andsternum remain generally intact. These terms are intended to distinguisha gross thoracotomy, such as a median sternotomy, wherein the sternumand/or one or more ribs are cut or removed from the rib cage. It shouldbe understood that one or more ribs may be retracted to widen theintercostal space between adjacent ribs without departing from the scopeof the invention.

[0076] Proximate the distal end of each probe is an elongated ablatingend 70 having an ablating surface 65 formed to transmurally ablate hearttissue. Access to the selected portions of the atria of the heart H areprovided by the specially shaped shafts 66 and ablating ends 70 whichare configured to position the elongated ablating surface 65 through thechest wall of patient P and through a strategically positionedpenetration in the muscular wall of the patient's heart H for ablativecontact with a selected portion of an interior surface of the muscularwall. Subsequent contact of the ablating surface 65 with specificselected wall portions of the atria enable selected, localizedtransmural ablation thereof.

[0077] In a preferred embodiment the probes 57 form the lesions byfreezing the heart tissue. Although freezing is a preferred method ofablating tissue, the probe 57 may use any other method such as RFablation, ultrasound, microwave, laser, localized delivery of chemicalor biological agents, light-activated agents, laser ablation orresistance heating ablation. Regarding the localized delivery ofchemical or biological agents, the device may include an injectiondevice capable of injecting the chemical or biological agent onto orinto the desired tissue for localized ablation thereof. The source ofthe chemical or biological agent may be stored in a reservoir containedin the probe or be stored in an external reservoir coupled to theinjecting end of the probe.

[0078] When the probe freezes tissue during ablation, an opposite end ofthe probe has a fitting 71 formed for releasable coupling to an end of adelivery hose which in turn is coupled to a source (both of which arenot shown) of cryogenic media. A threaded portion 72 of the fitting isformed for removable mounting to the delivery hose and further providescommunication with the cryogenic media for both delivery to and exhaustfrom the probe.

[0079] As shown in FIG. 6, each probe includes an elongated shaft 66sufficiently dimensioned and shaped to enable manual manipulation of theablating end 70 into contact with the desired heart tissue from outsidethe thoracic cavity. The shaft 66 is preferably tubular-shaped anddefines a communication passageway 73 extending therethrough whichprovides both delivery and exhaust of the cryogen to and from theablating end 70. Communication passageway 73 extends fully from thefitting 71 (FIG. 4) to a closed-end boiler chamber 75 where the cryogenexits the ablating end 70. Preferably, the tubular shaft 66 includes anouter diameter in the range of about 2.0 mm to about 5.0 mm, and mostpreferably about 4.0 mm; while the inner diameter is in the range ofabout 1.5 mm to about 4.5 mm, and most preferably about 3.0 mm.

[0080] Concentrically positioned in the communication passageway 73 ofeach probe is a delivery tube 76 (FIG. 6) which extends from the fitting71 to proximate the boiler chamber 75 for communication therebetweenenabling delivery and dispersion of the cryogen to the boiler chamber.The proximal end of delivery tube 76 is coupled to the cryogen liquidsource through a conventional fitting for delivery of the cryogenthrough a delivery passageway 77. The outer diameter of delivery tube 76is dimensioned such that an annular exhaust passageway 78 is formedbetween the outer diameter of the delivery tube 76 and the innerdiameter of the tubular shaft 66. This exhaust passageway 78 provides aport through which the expended cryogen exiting the boiler chamber canbe exhausted. Preferably, the delivery tube 76 includes an outerdiameter in the range of about 1.4 mm to about 3.0 mm, and mostpreferably about 2.0 mm; while the inner diameter is in the range ofabout 1.15 mm to about 2.75 mm, and most preferably about 1.50 mm.

[0081] The shaft of each probe 56 is specifically formed and shaped tofacilitate performance of one or more of the particular procedures to bedescribed in greater detail below. However, due to the nature of theprocedure and the slight anatomical differences between patients, eachprobe may not always accommodate a particular patient for the designatedprocedure. Accordingly, it is highly advantageous and desirable toprovide an exhaust shaft 66 and delivery tube 76 combination which ismalleable. This material property permits reshaping and bending of theexhaust shaft and delivery tube as a unit to reposition the ablatingsurface for greater ablation precision. Moreover, the shaft must becapable of bending and reshaping without kinking or collapsing. Suchproperties are especially imperative for the devices employed in thepulmonary vein isolation lesion formation which are particularlydifficult to access.

[0082] This malleable material, for example, may be provided by certainstainless steels, NiTi or a shape memory alloy in its superelastic statesuch as a superelastic alloy. Moreover, the shaft portion, with theexception of the ablating surface, may be composed of a polymer materialsuch as plastic which of course exhibits favorable thermoplasticdeformation characteristics. Preferably, however, the exhaust anddelivery shafts 66 and 76 are composed of bright annealed 304 stainlesssteel. The delivery tube 76 may also be composed of NiTi or othersuperelastic alloy.

[0083] To prevent or substantially reduce contact between the concentrictubes during operation, due to resonance or the like, the delivery tube76 may be isolated and separated from contact with the inner walls ofthe exhaust shaft 66 by placing spacers around the delivery tube. Thesespacers may be provided by plastic or other polymer material.Alternatively, the delivery tube may be brazed or welded to one side ofthe inner wall of the exhaust shaft 66 along the longitudinal lengththereof to resist vibrational contact, as illustrated in FIG. 8.

[0084] In accordance with the present invention, the lesions formed bythis system and procedure are generally elongated in nature. Theablating end 70 is thus provided by an elongated ablating surface 65which extends rearwardly from the distal end a distance of at leastabout seven (7) times to about thirty (30) times the outer diameter ofthe ablating end, which incidentally is about the same as the outerdiameter of the shaft 66. Hence, the length of the ablating surface isat least three (3) cm long, more preferably at least four (4) cm long,and most preferably at least five (5) cm long. Alternatively, theablating surface 65 has a length of between about three (3) cm to abouteight (8) cm.

[0085] In most applications, uniform cryothermic cooling along the fulllength of the ablating surface is imperative for effective operation.This task, alone, may be difficult to accomplish due primarily to therelatively small internal dimensions of the probe, as well as thegenerally curved nature of the boiler chambers in most of the cryoprobes(FIG. 4). FIG. 6 represents a typical cross-sectional view of anablating end 70 of one of the probe devices of the present invention inwhich the ablating surface 65 is formed to contact the heart tissue forlocalized, transmural ablation thereof. Ablating end 70 therefore ispreferably provided by a material exhibiting high thermal conductivityproperties suitable for efficient heat transfer during cryogenic coolingof the tip. Such materials preferably include silver, gold and oxygenfree copper or the like.

[0086] The ablating end 70 is preferably provided by a closed-end,elongated tube having an interior wall 80 which defines the boilerchamber 75, and is about 1.0 mm to about 1.5 mm thick, and mostpreferably about 1.25 mm thick. This portion is specifically shaped foruse in one or more ablation procedures and is formed for penetrationthrough the muscular walls of the heart. The distal end of exhaust shaft66 is preferably inserted through an opening 81 into the boiler chamber75 such that the exterior surface 82 at the tip of the exhaust shaft 66seatably abuts against the interior wall 80 of the ablating end 70 formounting engagement therebetween Preferably, silver solder or the likemay be applied to fixably mount the ablating end to the end of theexhaust shaft. Alternatively, the proximal end of ablating end 70 can bemounted directly to the distal end of exhaust shaft 66 (i.e., in anend-to-end manner) using electron-beam welding techniques. In eithermounting technique, a hermetic seal must be formed to eliminate cryogenleakage.

[0087] Proximate the distal end of delivery tube 76 is a deliveryportion 83 which extends through the opening 81 and into boiler chamber75 of the ablating end 70. This closed-end delivery portion includes aplurality of relatively small diameter apertures 85 which extend throughthe delivery portion 83 into delivery passageway 77 to communicate thepressurized cryogen between the delivery passageway and the boilerchamber 75. Using the Joule-Thompson effect, the cryogen flows throughthe delivery passageway in the direction of arrow 86 and into thedelivery portion 83 where the cryogen expands through the apertures fromabout 600-900 psi to about 50-200 psi in the boiler chamber. As thecryogen expands, it impinges upon the interior wall 80 of the ablatingend cooling the ablating surface 65. Subsequently, the expended cryogenflows in the direction of arrow 87 passing through the exhaustpassageway 78 and out through the delivery hose.

[0088] The number of apertures required to uniformly cool the ablatingend is primarily dependent upon the length of the boiler chamber 75, thediameter of the apertures, the type of cryogen employed and the pressureof the cryogen. Generally, for the preferred cryogen of nitrous oxide(N₂O), these delivery apertures 85 are equally spaced-apart at about 5mm to about 12 mm intervals, and extend from the proximal end of theboiler chamber to the distal end thereof. The preferred diameters of theapertures 85 range from about 0.004 inch to about 0.010 inch. Thesediameters may vary of course.

[0089] For most probes, three to four apertures or sets of aperturesspaced-apart longitudinally along delivery end portion are sufficient.Only one aperture 85 may be required at each longitudinal spacedlocation along the delivery portion 83 (FIG. 8). This one aperture maybe strategically positioned radially about the delivery portion todirect the stream of cryogen onto the portion of the interior wall 80directly beneath or near the predetermined portion of the ablatingsurface 65 which is to contact the heart wall tissue for a particularprocedure. Hence, the spaced-apart apertures may be strategicallypositioned to collectively direct the cryogen onto particular surfacesof the ablating end to assure maximum cooling of those portions. In someinstances, however (as shown in FIG. 7), more than one aperture 85 maybe radially positioned about the delivery portion 83 at any onelongitudinal spaced location, proximate a plane extending transverselytherethrough, for additional cryogenic cooling of the ablating surface.This may be especially important where the probe is to be employed inmore than one procedure.

[0090] Due to the elongated and curved nature of the ablating surface65, it is difficult to maintain a generally uniform temperature gradientalong the desired portions of the ablating surface during cryogeniccooling. This may be due in part to the pressure decrease in thedelivery passageway 77 of the delivery portion 83 as the cryogen passestherethrough. To compensate for this pressure loss as the cryogen passesthrough the delivery portion, the diameters of the apertures 85, 85′,85″ etc., may be slightly increased from the proximal end of thedelivery portion 83 to the distal end thereof. Thus, as the cryogentravels through the delivery portion 83 of the delivery tube, a moreuniform volume of cryogen may be distributed throughout the boilerchamber 75 even though the cryogenic pressure incrementally decreasesfrom the proximal end of the delivery portion 83.

[0091] Moreover, the delivery volume of the cyrogenic cooling also maybe controlled by varying the number of apertures at particular portionsof the ablating end i.e., increasing or decreasing the number ofapertures at a particular location. This directed cooling will have alocalized cooling effect, and is exemplified in the ablating end 70 ofFIG. 4. In this embodiment, the increased number of apertures along theinner bight portion 88 of delivery portion 83 delivers a more direct andgreater volume of cryogen against the inner bight portion 88, ascompared to the outer bight portion 90.

[0092] An insulative coating or tubing 89 is preferably includedextending circumferentially around portions of the cryoprobe shaft 66near the ablation end 70. This insulative tubing provides an insulatorybarrier around shaft 66 to prevent inadvertent direct contact betweenthe shaft, which will be cooled by the expended cryogen flowing throughthe exhaust passageway 75, and any organs or tissue of the percutaneouspenetration. The insulative tubing is preferably spaced from the shaft66 to define an air gap between the inner surface of the tubing and theouter surface of the shaft.

[0093] The insulative tubing 89 preferably extends around the elongatedshaft 66 from the base of the ablation end 70 to the fitting 71. In someinstances, however, the tubing may only need to extend from the base ofthe ablation end to a midportion of the elongated shaft. The insulativetubing 89 is preferably provided by heat shrink polyolefin tubing,silicone, TEFLON@, or the like.

[0094] In the preferred form, as shown in FIG. 7, the transverse,cross-sectional dimension of the ablating end 70 is circular-shapedhaving a substantially uniform thickness. However, it will be understoodthat the ablating surface 65 may include a generally flat contactsurface 91 formed for increased area contact with the heart tissuewithout requiring a substantial increase in the diameter of the ablatingsurface. As best viewed in FIGS. 8A-8C, contact surface 91 may begenerally flat or have a much larger radius than that of the ablatingend. Moreover, the spaced-apart apertures 85 are preferably oriented andformed to deliver the cryogen into direct impingement with the undersideof the contact surface 91 of ablating end 70. In this arrangement, thedelivery portion 83 of the delivery tube 76 may be mounted to one sideof the interior wall 80, as set forth above.

[0095] Alternatively, the contact surface can be provided by a bluntededge or the like to create a relatively narrow lesion. Although notillustrated, the transverse cross-sectional dimension of this embodimentwould appear teardrop-shaped.

[0096] FIGS. 6A-6D illustrate an embodiment of the probe 57 in which aninsulative jacket or sleeve 304 is disposed on the probe so as to bemovable relative thereto. The sleeve 304 has a window or cut-out portion305 which exposes a selected area of the probe 57. FIG. 6A shows thesleeve 304 located around the probe shaft, while FIG. 6B shows thesleeve after it has been slid over part of the probe ablating surface65. FIG. 6C shows the sleeve 304 after it has been slid completely overthe ablating surface 65 to a position where the window 305 exposes onearea of the surface 65 for ablating tissue. FIG. 6D shows the sleeve 304rotated to a different position where the window 305 exposes a differentarea of the surface 65 for ablating tissue. The sleeve 304 may beslidable and rotatable relative to the probe as show in FIGS. 6A-6D.Alternatively, the sleeve 304 may be fixed axially with respect to theprobe 57 but rotatable relative thereto so that the window is able toexpose different areas of the ablating surface. Further still, thesleeve 304 may be fixed on the probe 57 such that only a selected areaof ablation surface 65 is exposed through window 305. The sleeve 304 maybe formed of any suitable material, for example, a flexible polymerhaving low thermal conductivity.

[0097] The preferred cryogen employed in the devices of the presentinvention is nitrous oxide (N₂O) which is normally stored in acompressed gas cylinder (not shown). Other cryogenic fluids may beemployed which include liquid nitrogen or liquified air stored in aDewar vessel (not shown), freon 13, freon 14, freon 22, and normallygaseous hydrocarbons.

[0098] To cool the ablating end of the cryoprobe, cryogen is selectivelydelivered through the delivery passageway 77 of delivery tube 76 intothe delivery conduit thereof. As the cryogen flows through deliveryapertures 85, the gas expands into the boiler chamber 75, cooling theablating surface using the well known Joule-Thompson effect. Theelongated ablating surface 65 is then immediately cooled to atemperature of preferably between about −50° C. to about −80° C., whennitrous oxide is employed. Direct conductive contact of the cooled,elongated ablating surface 65 with the selected heart tissue causescryogenic ablation thereof. Subsequently, a localized, elongated,transmural lesion is formed at a controlled location which sufficientlyprevents or is resistant to electrical conduction therethrough.

[0099] To assure preclusion of electrical conduction of reentrantpathways in the atria, the lesions must be transmural in nature. Hence,the minimum length of time for conductive contact of the ablatingsurface with the selected heart tissue necessary to cause localized,transmural ablation thereof is to a large degree a function of thethickness of the heart wall tissue, the heat transfer loss due do theconvective and conductive properties of the blood in fluid contact withthe ablating surface, as well as the type of cryogen employed and therate of flow thereof. In most instances, when employing nitrous oxide asthe cryogen, tissue contact is preferably in the range of about 2-4minutes.

[0100] As mentioned, while the closed-heart surgical system andprocedure of the present invention may be performed through open-chestsurgery, the preferred technique is conducted through closed-chestmethods. FIGS. 5 and 9 illustrate system 56 for closed-chest,closed-heart surgery positioned in a patient P on an operating table T.The patient is prepared for cardiac surgery in the conventional manner,and general anesthesia is induced. To surgically access the rightatrium, the patient is positioned on the patient's left side so that theright lateral side of the chest is disposed upward. Preferably, a wedgeor block W having a top surface angled at approximately 20° to 45° ispositioned under the right side of the patient's body so that the rightside of the patient's body is somewhat higher than the left side. Itwill be understood, however, that a similar wedge or block W ispositioned under the left side of patient P (not shown) when performingthe surgical procedure on the left atrium In either position, thepatient's right arm A or left arm (not shown) is allowed to rotatedownward to rest on table T, exposing either the right lateral side orthe left lateral side of the patient's chest.

[0101] Initially one small incision 2-3 cm in length is made between theribs on the right side of the patient P, usually in the third, fourth,or fifth intercostal spaces, and most preferably the fourth as shown inFIG. 11A. When additional maneuvering space is necessary, theintercostal space between the ribs may be widened by spreading of theadjacent ribs. A thoracoscopic access device 68 (e.g. a retractor,trocar sleeve or cannulae), providing an access port 67, is thenpositioned in the incision to retract away adjacent tissue and protectit from trauma as instruments are introduced into the chest cavity. Thisaccess device 68 has an outer diameter preferably less than 14 mm and anaxial passage of a length less than about 12 mm. It will be understoodto those of ordinary skill in the art that additional thoracoscopictrocars or the like may be positioned within intercostal spaces in theright lateral chest inferior and superior to the retractor 68, as wellas in the right anterior (or ventral) portion of the chest if necessary.In other instances, instruments may be introduced directly throughsmall, percutaneous intercostal incisions in the chest.

[0102] Referring again to FIGS. 5 and 9, the retractor 68, such as thatdescribed in detail in commonly assigned U.S. patent application Ser.No. 08/610,619 filed Mar. 4, 1996, surgical access to the body cavity ofpatient P through the first intercostal percutaneous penetration 92 inthe tissue 93. Briefly, retractor 68 includes an anchoring frame 95having a passageway 67 therethrough which defines a longitudinalretractor axis. The anchoring frame 95 is positionable through theintercostal percutaneous penetration 92 into the body cavity. A flexibletensioning member 96 is attached to anchoring frame 95 and extendiblefrom the anchoring frame out of the body through intercostal penetration92 to deform into a non-circular shape when introduced between two ribs.The tensioning member 96 is selectively tensionable to spread the tissueradially outward from the longitudinal axis. Hence, it is the tensionimposed on the flexible tensioning member 96 which effects retraction ofthe tissue, rather than relying on the structural integrity of a tubularstructure such as a trocar sheath.

[0103] Once the retractor 68 has been positioned and anchored in thepatient's chest, visualization within the thoracic cavity may beaccomplished in any of several ways. An endoscope 97 (FIG. 5) ofconventional construction is positioned through a percutaneousintercostal penetration into the patient's chest, usually through theport of the soft tissue retractor 68. A video camera 98 is mounted tothe proximal end of endoscope 97, and is connected to a video monitor100 for viewing the interior of the thoracic cavity. Endoscope 97 ismanipulated so as to provide a view of the right side of the heart, andparticularly, a right side view of the right atrium. Usually, anendoscope of the type having an articulated distal end such as theDistalcam 360, available from Welch-Allyn of Skameateles Falls, N.Y., ora endoscope having a distal end disposed at an angle between 30_(i) and90_(i) will be used, which is commercially available from, for example,Olympus Corp., Medical Instruments Division, Lake Success, N.Y. A lightsource (not shown) is also provided on endoscope 97 to illuminate thethoracic cavity.

[0104] Further, the surgeon may simply view the chest cavity directlythrough the access port 67 of the retractor 68. Moreover, during theclosed heart procedure of the present invention, it may be desirable tovisualize the interior of the heart chambers. In these instances atransesophageal echocardiography may be used, wherein an ultrasonicprobe is placed in the patient's esophagus or stomach to ultrasonicallyimage the interior of the heart. A thoracoscopic ultrasonic probe mayalso be placed through access device 68 into the chest cavity andadjacent the exterior of the heart for ultrasonically imaging theinterior of the heart.

[0105] An endoscope may also be employed having an optically transparentbulb such as an inflatable balloon or transparent plastic lens over itsdistal end which is then introduced into the heart. As disclosed incommonly assigned, co-pending U.S. patent application Ser. No.08/425,179, filed Apr. 20, 1995, the balloon may be inflated with atransparent inflation fluid such as saline to displace blood away fromdistal end and may be positioned against a site such a lesion, allowingthe location, shape, and size of cryolesion to be visualized.

[0106] As a further visualization alternative, an endoscope may beutilized which employs a specialized light filter, so that only thosewavelengths of light not absorbed by blood are transmitted into theheart. The endoscope utilizes a CCD chip designed to receive and reactto such light wavelengths and transmit the image received to a videomonitor. In this way, the endoscope can be positioned in the heartthrough access port 67 and used to see through blood to observe a regionof the heart. A visualization system based on such principles isdescribed in U.S. Pat. No. 4,786,155, which is incorporated herein byreference.

[0107] Finally, the heart treatment procedure and system of the presentinvention may be performed while the heart remains beating. Hence, thetrauma and risks associated with cardiopulmonary bypass (CPB) andcardioplegic arrest can be avoided. In other instances, however,arresting the heart may be advantageous. Should it be desirable to placethe patient on cardiopulmonary bypass, the patient's right lung iscollapsed and the patient's heart is arrested. Suitable techniques forarresting cardiac function and establishing CPB without a thoracotomyare described in commonly-assigned, co-pending U.S. patent applicationSer. No. 08/282,192, filed Jul. 28, 1994 and U.S. patent applicationSer. No. 08/372,741, filed Jan. 17, 1995, all of which are incorporatedherein by reference. Although it is preferred to use the endovascularsystems described above, any system for arresting a patient's heart andplacing the patient on CPB may be employed.

[0108] As illustrated in FIG. 10, CPB is established by introducing avenous cannula 101 into a femoral vein 102 in patient P to withdrawdeoxygenated blood therefrom. Venous cannula 101 is connected to acardiopulmonary bypass system 104 which receives the withdrawn blood,oxygenates the blood, and returns the oxygenated blood to an arterialreturn cannula 105 positioned in a femoral artery 106.

[0109] A pulmonary venting catheter 107 may also be utilized to withdrawblood from the pulmonary trunk 108. Pulmonary venting catheter 107 maybe introduced from the neck through the interior jugular vein 110 andsuperior vena cava 111, or from the groin through femoral vein 102 andinferior vena cava 103. An alternative method of venting blood frompulmonary trunk 108 is described in U.S. Pat. No. 4,889,137, which isincorporated herein by reference. In the technique described therein, anendovascular device is positioned from the interior jugular vein in theneck through the right atrium, right ventricle, and pulmonary valve intothe pulmonary artery so as to hold open the tricuspid and pulmonaryvalves.

[0110] For purposes of arresting cardiac function, an aortic occlusioncatheter 113 is positioned in a femoral artery 106 by a percutaneoustechnique such as the Seldinger technique, or through a surgicalcut-down. The aortic occlusion catheter 113 is advanced, usually over aguidewire (not shown), until an occlusion balloon 115 at its distal endis disposed in the ascending aorta 116 between the coronary ostia andthe brachiocephalic artery. Blood may be vented from ascending aorta 116through a port 120 at the distal end of the aortic occlusion catheter113 in communication with an inner lumen in aortic occlusion catheter113, through which blood may flow to the proximal end of the catheter.The blood may then be directed to a blood filter/recovery system 121 toremove emboli, and then returned to the patient's arterial system viaCPB system 104.

[0111] When it is desired to arrest cardiac function, occlusion balloon115 is inflated until it completely occludes ascending aorta 116,blocking blood flow therethrough. A cardioplegic fluid such as potassiumchloride (KCl) is preferably mixed with oxygenated blood from the CPBsystem and then delivered to the myocardium in one or both of two ways.Cardioplegic fluid may be delivered in an anterograde manner, retrogrademanner, or a combination thereof. In the anterograde delivery, thecardioplegic fluid is delivered from a cardioplegia pump 122 through aninner lumen in aortic occlusion catheter 113 and the port 120 distal toocclusion balloon 115 into the ascending aorta upstream of occlusionballoon 115. In the retrograde delivery, the cardioplegic fluid may bedelivered through a retroperfusion catheter 123 positioned in thecoronary sinus from a peripheral vein such as an internal jugular veinin the neck.

[0112] With cardiopulmonary bypass established, cardiac functionarrested, and the right lung collapsed, the patient is prepared forsurgical intervention within the heart H. At this point in theprocedure, whether cardiac function is arrested and the patient isplaced on CPB, or the patient's heart remains beating, the hearttreatment procedure and system of the present invention remainsubstantially similar. The primary difference is that when the procedureof the present invention is performed on an arrested heart, the bloodpressure in the internal chambers of the heart is significantly less.Hence, it is not necessary to form a hemostatic seal between the deviceand the heart wall penetration to inhibit blood loss through thepenetration thereby reducing or eliminating the need for purse-stringsutures around such penetrations, as will be described below.

[0113] In the preferred embodiment, however, the procedure is conductedwhile the heart is still beating. Accordingly, it is necessary to form ahemostatic seal between the ablation device and the penetration.Preferably, purse-string sutures 58, 60, 61, 62 and 63 (FIGS. 3A and 3B)are placed in the heart walls at strategic or predetermined locations toenable introduction of the ablating probes into the heart whilemaintaining a hemostatic seal between the probe and the penetration.

[0114] As best viewed shown in FIG. 11A, in order to gain access to theright atrium of the heart, a pericardiotomy is performed usingthoracoscopic instruments introduced through retractor access port 67.Instruments suitable for use in this procedure, including thoracoscopicangled scissors 130 and thoracoscopic grasping forceps 131, aredescribed in commonly assigned U.S. Pat. No. 5,501,698, issued Mar. 26,1996, which is incorporated herein by reference.

[0115] After incising a T-shaped opening in the pericardium 132 (about5.0 cm in length across and about 4.0 cm in length down, FIG. 11A), theexterior of the heart H is sufficiently exposed to allow theclosed-chest, closed-heart procedure to be performed. To further aid invisualization and access to the heart H, the cut pericardial tissue 133is retracted away from the pericardial opening 135 with stay sutures 136(FIG. 11C) extending out of the chest cavity. This technique allows thesurgeon to raise and lower the cut pericardial wall in a manner whichreshapes the pericardial opening 135 and retracting the heart Hslightly, if necessary, to provide maximum access for a specificprocedure.

[0116] To install stay suture 136, a curved suture needle 137 attachedto one end of a suture thread 138 is introduced into the chest cavitythrough passageway 67 with of a thoracoscopic needle driver 140 (FIG.11B). Once the suture needle 137 and thread 138 have been driven throughthe cut pericardial tissue, the suture thread 138 is snared by a suturesnare device 141. This is accomplished by positioning a hooked end 142of suture snare device 141 through at least one additional percutaneousintercostal penetration 143 positioned about the chest to enablepenetration into the thoracic cavity. In the preferred arrangement, atrocar needle (not shown) is employed which not only forms thepenetration, but also provides access into the thoracic cavity withoutsnaring tissue during removal of the snare device.

[0117] Accordingly, both sides of the suture thread 138 are snared andpulled through the chest wall for manipulation of the stay suture fromoutside of the body cavity. The ends of the stay suture 136 are coupledto a surgical clamp (not shown) for angled manipulation and tensionadjusting. While only two stay sutures are illustrated, it will beappreciated that more stay sutures may be employed as needed to furthermanipulate the pericardial opening.

[0118] Turning now to FIG. 11C, a first 4-0 purse-string suture 58, forexample, is placed in the heart wall proximate the site at which it isdesired to initiate the first heart wall penetration 146 (FIG. 11D).Again, this is accomplished by using a thoracoscopic needle driver todrive the suture needle through the heart wall to form a running stitchin a circular pattern approximately 1.0-3.0 mm in diameter. Adouble-armed suture may also be used, wherein the suture thread 145(about 3 mm to about 10 mm in diameter) has needles (not shown) at bothends, allowing each needle to be used to form one semi-circular portionof the purse-string. Suture thread 138 is long enough to allow both endsof the suture to be drawn outside of the chest cavity once purse-stringsuture 58 has been placed. The suture needle is then cut from thread 145using thoracoscopic scissors.

[0119] To tension the purse-string suture 58, the suture threads 145 arepulled upon gathering the stitched circular pattern of tissue togetherbefore commencement of the formation of a penetration through the heartwall within the purse-string suture. One or a pair of thoracoscopiccinching instruments 147, such as a Rumel tourniquet, may be employed tograsp a loop of purse-string suture 58. As best viewed in FIG. 11D,cinching instrument 147 comprises a shaft 148 with a slidable hook 150at its distal end thereof for this purpose. Hook 150 may be retractedproximally to frictionally retain suture thread 145 against the distalend of shaft 148. By retracting or withdrawing the cinching instrument147, the purse-string suture 58 is cinched tightly, thereby gatheringheart wall tissue together to form a hemostatic seal.

[0120] The cinching instrument may be clamped in position to maintaintension on suture thread 145. Preferably, however, a slidable tensioningsleeve 151 (FIG. 11D), commonly referred to as a snugger, may beprovided in which the suture threads are positioned through a boreextending therethrough. The snugger is then slid along the suture threaduntil it abuts against the epicardial surface 152 of the heart wall. Thecinching instrument is then pulled proximally relative to tensioningsleeve 151 to obtain the desired degree of tension on suture thread 145.Tensioning sleeve 151 is configured to frictionally couple to suturethread 145 to maintain tension on the suture.

[0121] An incision device 153 is introduced through access device 68into the chest cavity for piercing the heart H. A blade 155 positionedon the distal end of a manipulating shaft 156 is advanced to pierce theheart wall within the bounds of purse-string suture 58. The blade 155 ispreferably about 5.0 mm in length and about 3.0 mm wide terminating atthe tip thereof. FIG. 11D illustrates that as the incision device 153 ismanually moved further into contact with the epicardial surface 152 ofthe heart wall, blade 155 will be caused to pierce therethrough to forma penetration of about 1.0-2.0 mm across.

[0122] In the preferred form, the blade 155 is rigidly mounted to shaft156 for direct one-to-one manipulation of the blade. Alternatively,however, the incision device may employ a spring loaded mechanism or thelike which advances the blade forwardly from a retracted position,retracted in a protective sleeve of the shaft, to an extended position,extending the blade outside of the sleeve and into piercing contact withthe tissue. In this embodiment, a button or the like may be providednear the proximal end of the shaft for operation of the blade betweenthe retracted and extended positions.

[0123] To facilitate formation of the penetration by the incisiondevice, a thoracoscopic grasping instrument (not shown) may be employedto grasp the heart wall near purse-string suture 58 to counter theinsertion force of blade 155 and incision device 153. As blade 155penetrates the heart wall, incision device 153 is advanced to extendtransmurally into the heart through the penetration 146 formed in heartwall.

[0124] As above-indicated in FIGS. 3A and 3B, the entire procedure ispreferably performed through a series of only five purse-strings sutures58, 60, 61, 62 and 63, and the corresponding cardiac penetrations 146,157, 158, 160 and 161 of which two penetrations 158, 160 arestrategically positioned in the right atrium RA; one penetration 161 ispositioned in the left atrium LA; and two penetrations 158, 160 arepositioned near the pulmonary vein trunk 108. Such small incisions aresignificantly less traumatic on the heart tissue muscle than theelongated transmural incisions of the prior MAZE techniques.

[0125] Referring now to FIGS. 3A, 12A-12C and 13, the system andprocedure of the present invention will be described in detail.Preferably, the first series of lesions is formed on the right atrium RAto form a posterior longitudinal right atrial lesion 50 and a tricuspidvalve annulus lesion 51. It will be appreciated, however, that thetransmural lesions can be formed in any order without departing from thetrue spirit and nature of the present invention.

[0126] By strategically placing the first heart wall penetration 146 offirst purse-string suture 58 at the base of the right atrial appendageRAA where the anticipated intersection between the longitudinal rightatrial lesion 50 and the tricuspid valve annulus lesion 51 are to occur(FIG. 12C), these two lesions can be formed through a series of threeindependent ablations. As best viewed in FIG. 12A, the upper sectionsegment 162 (half of the longitudinal right atrial lesion 50) is formedusing a right angle probe 163 (FIG. 24) having a first elbow portion 166positioned between the generally straight elongated shaft 66 and thegenerally straight ablating end. The first elbow portion has an arclength of about 85° to about 95° and a radius of curvature of about 3.2mm to about 6.4 mm. The ablating end 70 is preferably about 2.0 mm toabout 4.0 mm in diameter, and about 2.0 cm to about 6.0 cm in length. Inthis configuration, the ablating surface 65 extends, circumferentially,from a distal end 165 thereof to just past an elbow portion 166 of theright angle probe 163.

[0127] Initially, the probe ablating end 70 and the shaft 66 of probe163 is introduced into the thoracic cavity through the retractor 68 bymanipulating a handle (not shown) releasably coupled to fitting 71. Tofacilitate location of the first penetration with the probe, the distalend 165 is guided along the shaft 156 of incision device 153 (FIG. 11D)until positioned proximate the first penetration 146. Subsequently, theblade 155 of incision device is withdrawn from the first penetrationwhereby the distal end of the probe is immediately inserted through thefirst penetration. Not only does this technique facilitate insertion ofthe probe but also minimizes loss of blood through the penetration.

[0128] Once the distal end 165 of the right angle probe 163 has beeninserted and negotiated through the first penetration, the firstpurse-string suture may require adjustment to ensure the formation of aproper hemostatic seal between the penetration and the shaft of theprobe. If the loss of blood should occur, the purse-string suture can beeasily tightened through either a Rumel tourniquet or tensioning sleeve151.

[0129]FIG. 12A best illustrates that the right angle probe 163 ispreferably inserted through the penetration 146 until an elbow portion166 thereof just passes through the penetration. Although the angularmanipulation of the end of the right angle probe is limited due to theaccess provided by the retractor, the insertion should be easilyaccommodated since the heart wall tissue of the right atrium issubstantially resilient and flexible. Again, a thoracoscopic graspinginstrument (not shown) may be employed to grasp the heart wall near thefirst purse-string suture 58 to counter the insertion force of rightangle probe 163 through the first penetration 146. Once the ablating endis inserted to the desired depth and through the assistance of eitherdirect viewing or laparoscopic viewing, the elongated ablating end 70 isoriented to position a longitudinal axis thereof generally parallel tothe right atrioventricular groove. This upper section segment 162 of thelongitudinal right atrial lesion 50 extends generally from the firstpenetration 146 to the orifice of the superior vena cava 111. Byretracting the probe rearwardly out of the passageway of the retractor68 generally in the direction of arrow 167, the ablating surface will becaused to sufficiently contact the right atrial endocardium.

[0130] As mentioned above, the probe may use any method to ablate theheart tissue. When using a cryogenic ablating system, the cryogen storedin a Dewar vessel or pressurized cylinder is selectively released whereit passes into the boiler chamber 75 of the device 163, thereby coolingthe probe ablating surface for localized ablation of heart tissue. Aspreviously stated, to warrant proper transmural ablation of the interiorwall of the right atrium, continuous contact of the ablating surfacetherewith should occur for about 2-4 minutes. Visually, however,transmural cryosurgical ablation of the tissue is generally representedby a localized lightening or discoloration of the epicardial surface 168of the ablated heart tissue which can be directly viewed through theaccess port 67 of access device 68. This method of determiningcryoablation of the tissue can be used in combination with the timedprobe contact therewith. As a result, the upper section segment 162 ofthe longitudinal right atrial lesion 50 will be formed.

[0131] Once the desired elongated portion of heart tissue has beenablated, caution must be observed before the ablating surface 65 probecan be separated from the contacted endocardial surface of the hearttissue. Due to the extremely low temperatures of the ablating surface(i.e., about −50° to about −80°) and the moistness of the heart tissue,cryoadhesion can occur. Accordingly, the probe tip must be properlythawed or defrosted to enable safe separation after the tissue has beenproperly ablated.

[0132] For example, after sufficient transmural cryoablation of theheart tissue, thawing is commenced by halting the flow of cryogenthrough the probe and maintaining continuous contact between the probeablating surface and the cryoablated tissue. After about 10-20 seconds,and preferably about 15 seconds, the conductive and convective heattransfer or heat sink effect from the surrounding tissue and blood issufficient to reverse the cryoadhesion. Of course, it will beappreciated that such heat transfer is more efficient when the procedureis performed on a beating heart as opposed to an arrested heart.Alternatively, the system may also be provided with a defrost mode whichserves to warm the tissue to room temperature. This may be accomplishedby raising the pressure of the cryogen adjacent the ablating surfacesuch that its temperature increases, for example, by restricting theexhaust gas flow.

[0133] Furthermore, to facilitate thawing of the exterior surface of theablated tissue, a room temperature or slightly heated liquid may bewetted or impinged upon the exterior surface of the ablated area. In thepreferred embodiment, such liquid may include saline or other non-toxicliquid introduced into the thoracic cavity through the retractorpassageway 67.

[0134] Generally, multiple lesions can be formed through a singlepurse-string suture either through the use of assorted uniquely shapedablating devices or through the manipulation of a single ablatingdevice. Accordingly, while maintaining the hemostatic seal between theprobe shaft and the penetration, the respective ablating device can bemanipulated through the respective penetration to strategically contactthe corresponding elongated ablating surface with another selectedportion of the interior surface of the muscular wall for transmuralablation thereof. For instance, without removing the right anglecryoprobe from the first penetration, the ablating surface 65 is rotatedapproximately 180° about the longitudinal axis to re-position the distalend generally in a direction toward the orifice of the inferior venacava 103. As shown in FIG. 12B, such positioning enables the formationof the remaining lower section segment 170 of the longitudinal rightatrial lesion 50. However, since the lower section segment 170 of thelesion is shorter in length than that of the upper section segment, thelength of the elongated ablating surface contacting the interior wall ofright atrium must be adjusted accordingly. This length adjustment isaccomplished by partially withdrawing the probe ablating surface 65 fromthe first penetration 146 by the appropriate length to ablate the lowersection segment 170. Due to the substantial flexibility and resiliencyof the heart tissue, such maneuverability of the probe and manipulationof the tissue is permissible.

[0135] Similar to the formation of the upper section segment 162 of thelongitudinal right atrial lesion 50, the right angle probe 163 isretracted rearwardly, generally in the direction of arrow 167, causingthe ablating surface 65 of the probe to sufficiently contact theendocardium of the right atrium. After the cryogen has continuouslycooled the elongated ablating surface 65 of the probe for about 2-4minutes, the remaining lower section segment of the longitudinal rightatrial lesion 50 will be formed. Thereafter, the probe is defrosted toreverse the effects of cryoadhesion. It will be understood that while itis beneficial to employ the same right angle probe to perform both theupper and lower section segments of the longitudinal right atriallesion, a second right angle probe having an ablating surface shorter inlength than that of the first right angle probe could easily beemployed.

[0136] Utilizing the same first penetration, the tricuspid valve annuluslesion 51 can be formed employing one of at least two probes.Preferably, the right angle probe 163 may again be used by rotating theelongated ablating surface 65 about the probe shaft longitudinal axis toreposition the distal end trans-pericardially, generally in a directionacross the lower atrial free wall and toward the tricuspid valve 171(FIGS. 12C and 13). The distal end of the probe ablating surface 65,however, must extend all the way to the tricuspid valve annulus 172.Hence, in some instances, due to the limited maneuvering space providedthrough the retractor passageway, the formation of the tricuspid valveannulus lesion 51 with the right angle probe may be difficult toperform.

[0137] In these instances, a special shaped tricuspid valve annulusprobe 173 (FIGS. 13 and 25) is employed which is formed and dimensionedto enable contact of the probe ablating surface 65 with appropriateportion of the right atrium interior wall all the way from the firstpenetration 146 to the tricuspid valve annulus 172 to form the tricuspidvalve annulus lesion 51. The ablating end 70 and the shaft 66 of thisprobe cooperate to form one of the straighter probes 57 of the set shownin FIG. 4.

[0138]FIG. 25 best illustrates the tricuspid valve annulus probe 173which includes an elongated shaft 66 having a first elbow portion 166positioned between a generally straight first portion 175 and agenerally straight second portion 176 having a length of about 2.0 cm toabout 6.0 cm. The first elbow portion has an arc length of about 20° toabout 40° and a radius of curvature of about 13.0 cm to about 18.0 cm.Further, a second elbow portion 177 is positioned between the secondportion 176 and a third portion 178 of the shaft, angling the thirdportion back toward the longitudinal axis of the first portion 175 ofthe elongated shaft 66. The third portion 178 includes a length of about2.0 cm to about 6.0 cm, while the second elbow portion has an arc lengthof about 5° to about 20° and a radius of curvature of about 15.0 cm toabout 20.0 cm. The ablating end 70 is relatively straight and is coupledto the distal end of the third portion 178 of the elongated shaft 66 ina manner angling the ablating end back away from the longitudinal axisand having an arc length of about 5° to about 20° and a radius ofcurvature of about 13.0 cm to about 18.0 cm. The ablating end 70 isformed to extend from the first penetration and to the rim 172 of thetricuspid valve 171 from outside of the body cavity. For this probe, theablating surface 65 is preferably about 2.0 cm to about 6.0 cm inlength. It will be understood that while the illustrations anddescriptions of the probes are generally two dimensional, theconfigurations of the shaft and ablating end combinations could be threedimensional in nature.

[0139] Using the insertion technique employed by the right angle probe163 during the formation of the longitudinal right atrial lesion 50,upon withdrawal of the right angle probe from the first penetration 146,the distal end of the tricuspid valve annulus probe 173 is immediatelyinserted therethrough to facilitate alignment and minimize the loss ofblood.

[0140] Regardless of what instrument is employed, once the probeablating surface 65 is strategically oriented and retracted to contactthe endocardial surface, the cryogen is selectively released into theboiler chamber to subject the desired tissue to localized cryothermia.Due to the nature of the transmural ablation near the tricuspid valveannulus, the need for dividing all atrial myocardial fibers traversingthe ablated portion is effectively eliminated. Thus, the application ofthe nerve hook utilized in the prior MAZE procedures is no longernecessary.

[0141] As illustrated in FIG. 13, the distal end of the probe mustextend to the base of the tricuspid valve annulus 172. This lesion isdifficult to create since the right atrial free-wall in this region liesbeneath the atrioventricular groove fat pad (not shown). To facilitateorientation of the ablating end of the probe relative the valve annulusand to better assure the formation of a lesion which is transmural innature, an alternative tricuspid valve clamping probe 180 (FIG. 26) maybe employed rather than or in addition to the tricuspid valve annulusprobe 173.

[0142] This probe includes a primary shaft 66 and ablating end 70 whichare cooperatively shaped and dimensioned substantially similar to thetricuspid valve annulus probe 173. A clamping device 181 of clampingprobe 180 includes a mounting member 179 providing an engagement slot182 formed for sliding receipt of a pin member 184 coupled to primaryshaft 66. This arrangement pivotally couples the clamping device 181 tothe primary shaft 66 for selective cooperating movement of a clampingjaw portion 183 of the clamping device 181 and the ablating end 70between a released position, separating the clamping jaw portion fromthe ablating end 70 (phantom lines of FIG. 26), and a clamped position,urging the clamping jaw portion against the ablating end 70 (solid linesof FIG. 26).

[0143] The clamping jaw portion 183 is shaped and dimensionedsubstantially similar to the corresponding ablating end 70 to enableclamping of the heart tissue therebetween when the tricuspid valveclamping probe 180 is moved to the clamped position. At the opposite endof the clamping jaw portion 183 is a handle portion 185 for manipulationof the jaw portion between the released and clamped positions in apliers-type motion.

[0144] To perform this portion of the procedure using the tricuspidvalve clamping probe 180, the clamping jaw is moved toward the releasedposition to enable the distal end of the ablating end to be negotiatedthrough the first penetration 146. Using direct viewing through theretractor or visually aided with an endoscope, the ablating end is movedinto contact with the predetermined portion of the right atrium interiorwall all the way from the first penetration 146 to the tricuspid valveannulus 172. Subsequently, the clamping jaw portion is moved to theclamped position, via handle portion 185, to contact the epicardialsurface 168 of the heart wall opposite the tissue ablated by the probe.This arrangement increases the force against the ablating surface 65 tofacilitate contact and heat transfer. Cryogen is then provided to theboiler chamber to cool the ablating surface 65 thereby forming thetricuspid valve annulus lesion 51. Once the probe is removed from thefirst penetration 146, the first purse-string suture 58 is furthertightened to prevent blood loss.

[0145] The engagement slot 182 of mounting member 179 is formed topermit release of the pin member 184 therefrom. Hence, the clampingdevice 181 can be released from primary shaft 66 of the clamping probe180. This arrangement is beneficial during operative use providing thesurgeon the option to introduce the clamping probe 180 into the thoraciccavity as an assembled unit, or to first introduce the ablation end 70and primary shaft 66, and then introduce of the clamping device 181 forassembly within the thoracic cavity.

[0146] Turning now to FIG. 14, a second 4-0 purse-string suture 59 isplaced in the right atrial appendage RAA proximate a lateral midpointthereof in the same manner as above-discussed. This portion of the heartis again accessible from the right side of the thoracic cavity throughthe first access device 68. A second penetration 157 is formed centralto the second purse-string suture wherein blood loss from the secondpenetration is prevented through a second tensioning sleeve 186.Subsequently, the distal end of a right angle probe or a right atriumcounter lesion probe 187 (FIGS. 15 and 27), is inserted through secondpenetration 157 and extended into the right atrial appendage chamber.Second purse-string suture 59 may then be adjusted through secondtensioning sleeve 186, as necessary to maintain a hemostatic sealbetween the penetration and the probe.

[0147] The right atrium counter lesion probe 187 includes an elongatedshaft 66 having a first elbow portion 166 positioned between arelatively straight first portion 175 and a generally straight secondportion 176, whereby the first elbow portion has an arc length of about85° to about 95° and a radius of curvature of about 1.9 cm to about 3.2cm. The second portion is preferably about 2.0 cm to about 6.0 cm inlength. Further, a second elbow portion 177 is positioned between thesecond portion 176 and a generally straight third portion 178 of theshaft which is about 2.0 cm to about 6.0 cm in length. The second elbowportion has an arc length of about 40° to about 70° and a radius ofcurvature of about 3.2 cm to about 5.7 cm, angling the third portion 178back toward the longitudinal axis of the first portion 175 of theelongated shaft 66. The ablating end 70 is coupled to the distal end ofthe third portion 178 of the elongated shaft 66, and includes an arclength of about 85° to about 95° and a radius of curvature of about 6.0mm to about 19.0 mm to curve the distal end thereof back toward thelongitudinal axis of the first portion 175 of the shaft 66. Thus, thisequates to an ablating surface length of preferably about 4.0 cm toabout 8.0 cm in length.

[0148] This configuration enables the ablating end 70 of probe 187 toaccess the right lateral midpoint of the atrial appendage RAA where thesecond penetration 157 is to placed. FIGS. 14 and 15 best illustratethat the position of this second penetration 157 is higher up than thefirst penetration, relative the heart, when accessed from thepredetermined intercostal penetration 92. Upon insertion of the distalend of the probe through the second penetration 157, the ablating end 70is inserted into the right atrium chamber to the proper depth. Thehandle (not shown) of the probe 187 is manipulated and oriented fromoutside the thoracic cavity to position the distal end of the ablatingsurface 65 in a direction generally toward the first purse-string suture58. The probe is retracted rearwardly out of the retractor passageway,generally in the direction of arrow 167 in FIG. 14, to urge the ablatingsurface 65 of the probe into contact with the endocardial surface of theinterior wall of the right atrial appendage RAA. As a result, theperpendicular lesion 53 of the right atrial appendage is transmurallyformed.

[0149] The next lesion to be created is the anteromedial counter lesion55 which is to be formed through the second penetration 157. This lesionis positioned just anterior to the apex of the triangle of Koch and themembranous portion of the interatrial septum. Without removing the rightatrium counter lesion probe 187 from the second penetration 157, theelongated ablating surface 65 is urged further inwardly through thesecond penetration 157 toward the rear atrial endocardium of the rightatrial appendage RAA (FIG. 15). Upon contact of the ablating surface 65with the rear atrial wall, the probe 187 is slightly rotated upwardly inthe direction of arrows 191 in FIG. 15 to exert a slight force againstthe rear endocardial surface. Again, this ensures ablative contacttherebetween to enable formation of the anteromedial counter surgicallesion 55. Subsequently, the probe is properly defrosted and withdrawnfrom the second penetration 157 whereby the second purse-string suture59 is cinched tighter to prevent blood loss therefrom. It will beunderstood that since these two lesions are formed through cryothermictechniques, the need for atrial retraction and endocardial suturingemployed in connection with the formation of the transmural incision ofthe MAZE III procedure can be eliminated.

[0150] The next step in the procedure is an atrial septotomy to from ananterior limbus of the fossa ovalis lesion 192. The formation of thislesion will likely be performed without direct or laparoscopic visualassistance since the ablation occurs along internal regions of theinteratrial septum wall 193. Initially, as best illustrated in FIGS.16-18, two side-by-side purse-string sutures 61 and 62 are surgicallyaffixed to an epicardial surface 168 proximate the pulmonary trunk 108using the same techniques utilized for the first and second purse-stringsutures. The third purse-string suture 61 is positioned on one side ofthe septum wall 193 for access to the right atrium chamber, while thefourth purse-string suture 62 is positioned on the opposite side of theseptum wall for access to the left atrium chamber.

[0151]FIG. 17 further illustrates that the introduction of thoracoscopicinstruments and access to the third and fourth purse-strings arepreferably provided through the retractor 68. After the third and fourthtensioning sleeves 195, 196 have been mounted to the respective suturethreads, an incision device (not shown) is introduced into the thoraciccavity to incise the penetrations central to the respective purse-stringsutures. Due to the angle of the upper heart tissue surface relative theretractor 68, the incision device may incorporate an angled end or bladefor oblique entry through the heart wall tissue in the direction ofarrow 197 to form the third and fourth penetrations 158, 160 (FIG. 18).Alternatively, the incision device may include a blade end which iscapable of selective articulation for pivotal movement of the blade endrelative the elongated shaft. Use of a thoracoscopic grasping instrumentfacilitates grasping of the epicardium near the pulmonary trunk 108 tocounter the insertion force of the angled blade during formation of therespective penetrations 158, 160.

[0152] To create the lesion across the anterior limbus of the fossaovalis lesion 192, a special atrial septum clamping probe 198 (FIGS. 17and 28) is provided having opposed right angled jaw portions 200, 201formed and dimensioned for insertion through the corresponding third andfourth penetrations 158, 160 for clamping engagement of the anteriorlimbus of the fossa ovalis therebetween. As illustrated in FIG. 28, theatrial septum clamping probe 198 includes a primary clamping member 202having a generally straight, elongated clamping shaft 66 with a firstelbow portion 166 positioned between the clamping shaft 66 and agenerally straight outer jaw portion 200 (ablating end 70), whereby thefirst elbow portion has an arc length of about 85° to about 95° and aradius of curvature of about 3.2 mm to about 6.4 mm. The ablatingsurface extends just beyond elbow portion 166 and is of a length ofpreferably about 2.0 cm to about 6.0 cm.

[0153] In accordance with the special atrial septum clamping probe 198of the present invention, an attachment device 203 is coupled to theclamping shaft 205 which includes an inner jaw portion 201 formed anddimensioned to cooperate with the outer jaw portion 200 (i.e., theelongated ablating surface 65) of clamping member 202 for clampingengagement of the interatrial septum wall 193 therebetween (FIG. 17).Hence, the inner jaw portion and the outer jaw portion move relative toone another between a clamped condition (FIG. 17 and in phantom lines inFIG. 28) and an unclamped condition (FIG. 14A and in solid lines in FIG.28). In the unclamped condition, the inner jaw portion 201 of theattachment device 203 is positioned away from the outer jaw portion 200to permit initial insertion of the distal end 165 of the outer jawportion 200 of the clamping probe 198 into the fourth penetration 160,as will be discussed.

[0154] The attachment device 203 is preferably provided by a generallystraight, elongated attachment shaft 206 having a first elbow portion207 positioned between the attachment shaft 206 and a generally straightinner jaw portion 201. FIG. 28 best illustrates that the first elbowportion of inner jaw portion 201 has an arc length and radius ofcurvature substantially similar to that of the outer jaw portion 200.Further, the length of the inner jaw portion is preferably about 2.0 mmto about 6.0 mm.

[0155] In the preferred form, the attachment shaft 206 is slidablycoupled to the clamping shaft 66 through a slidable coupling device 208enabling sliding movement of the inner jaw portion 201 between theclamped and unclamped conditions. Preferably, a plurality of couplingdevices 208 are provided spaced-apart along the attachment shaft 206.Each coupling device includes a groove 210 (FIG. 29) formed for asliding, snap-fit receipt of the clamping shaft 66 therein for slidingmovement of the attachment device in a direction along the longitudinalaxis thereof.

[0156] The coupling devices are preferably composed of TEFLON®, plastic,polyurethane or the like, which is sufficiently resilient and bendableto enable the snap-fit engagement. Further, such materials includesufficient lubricating properties to provide slidable bearing support asthe clamping shaft 66 is slidably received in groove 210 to move innerjaw portion 201 between the clamped and unclamped conditions. Moreover,the coupling device configuration may permit rotational motion of theinner jaw portion 201 about the attachment shaft longitudinal axis, whenmoved in the unclamped condition. This ability further aids manipulationof the clamping probe 198 when introduced through the access device 68and insertion through the corresponding fourth penetration 160.

[0157] In the clamped condition, the inner jaw portion 201 is moved intoalignment with the outer jaw portion 200 of the clamping member 202 forcooperative clamping of the septum wall 193 therebetween. An alignmentdevice 211 is preferably provided which is coupled between the clampingmember 202 and the slidable attachment device 203 to ensure properalignment relative one another while in the clamped condition. This isparticularly necessary since the inner jaw portion 201 is capable ofrotational movement about the clamping shaft longitudinal axis, whenmoved in the unclamped condition. In the preferred embodiment, FIG. 30best illustrates that alignment device 211 is provided by a set ofspaced-apart rail members 212, 212′ each extending from the outer jawportion 200 to the clamping shaft 66 of the clamping member 202. Therail members 212, 212′ cooperate to define a slot 213 therebetween whichis dimensioned for sliding receipt of an elbow portion 207 of the innerjaw portion 201.

[0158] To further facilitate alignment between the inner jaw portion andthe outer jaw portion, the elbow portion 207 of the inner jaw portion201 may include a rectangular cross-section dimensioned for squaredreceipt in the slot 213 formed between the rail members 212, 212′.Alternatively, alignment may be provided by the inclusion of a lockingdevice positioned at the handle of the probe, or by indexing detentsincluded on the clamping shaft.

[0159] Due to the relatively close spacing and placement of the thirdand fourth purse-string sutures 61, 62 in relation to the heart and theretractor 68, substantial precision is required for simultaneousinsertion of the jaw portion distal ends 165, 215. This problem isfurther magnified by the limited scope of visualization provided byeither direct viewing through the retractor and/or with the endoscope.Accordingly, the septum clamping probe 198 includes staggered length jawportions which position the distal end 165 of the outer jaw portion 200slightly beyond the distal end 215 of the inner jaw portion 201 tofacilitate alignment and insertion through the penetrations 158, 160. Inthe preferred form, the right angled clamping member 202 is initiallyintroduced through access device 68 for positioning of the distal endproximate the fourth purse-string suture 62. Upon alignment of the outerjaw distal end 165 with the fourth penetration 160, the clamping member202 is manipulated in the direction of arrow 197 for insertion of theouter jaw portion partially into the left atrium chamber. The initialinsertion depth of the tip is to be by an amount sufficient to retainthe outer jaw portion 200 in the fourth penetration, while permittingthe shorter length inner jaw portion 201 of the attachment device tomove from the unclamped condition toward the clamped condition (FIGS.18A and 18B).

[0160] It will be understood that the slidable attachment device 203, atthis moment, will either be unattached to the right angle probe or willbe prepositioned in the unclamped condition. In the former event, theslidable attachment device 203 will be introduced through the accessdevice 68 and slidably coupled or snap fit to the clamping shaft 66 ofthe clamping member 202 via coupling devices 208. As the inner jawportion 201 is advanced in the direction of arrow 216 toward the clampedcondition, the attachment shaft 206 is rotated about its longitudinalaxis, if necessary, until the elbow portion 207 is aligned for receiptin the slot 213 formed between the spaced-apart rails members 212, 212′.In this arrangement, the inner jaw portion 201 will be aligned co-planarwith the outer jaw portion 200 of the clamping member 202.

[0161] The length of the inner jaw portion 201 is preferably shorterthan the length of the outer jaw portion 200 of clamping member 202(preferably by about 5 mm). With the distal end 165 of the outer jawportion 200 partially penetrating the fourth penetration 160 and thedistal end 215 of the inner jaw portion 201 aligned with the thirdpenetration 158 (FIG. 18B), the jaw portions are moved in the directionof arrow 197 to position the jaws through the penetrations, on oppositesides of the septum wall 193, and into the atrial chambers.

[0162] As shown in FIG. 17, the jaw portions 200, 201 are inserted to adesired depth whereby the clamping probe can be aligned to pass throughthe anterior limbus of the fossa ovalis. When properly oriented, the jawportions can be moved fully to the clamped position exerting an inwardlydirected force (arrows 216, 216′) toward opposed sides of theinteratrial septum wall 193. Subsequently, the cryogen is released intothe boiler chamber of the outer jaw portion of the clamping memberthereby cooling the ablating surface 65 and subjecting the septal wallto cryothermia.

[0163] Due in part to the substantial thickness of this heart tissue, tosecure proper transmural ablation of the interior septal wall of theright atrium, continuous contact of the ablating surface 65 therewithshould transpire for at least 3-4 minutes to create the anterior limbusof the fossa ovalis ablation. The clamping probe 198 and the septum wallare to be properly defrosted and subsequently withdrawn from the thirdand fourth penetrations 158, 160, whereby the third and fourthpurse-string sutures 61, 62 are cinched tighter to prevent blood losstherefrom.

[0164] The length of the outer jaw portion is preferably between about 3cm to about 5 cm, while the length of the inner jaw portion is generallyabout 5 mm less than the length of the outer jaw portion. Further, thediameter of the inner and outer jaw portions is preferably between about2-4 mm. The determination of the diameter and/or length of theparticular jaw portions and combinations thereof to be utilized willdepend upon the particular applications and heart dimensions.

[0165] The clamping arrangement of this probe enables a substantialclamping force urged between the two opposed jaw portions for moreefficient heat conduction. This configuration more effectively ablatesthe relatively thicker septum wall since greater leverage can beattained. Accordingly, in the preferred embodiment, only the outer jawportion 200 (i.e., the ablating surface 65) of the clamping member 202needs to be cooled to be effective. It will be appreciated, however,that the attachment device 203 may include the boiler chamber to coolthe inner jaw portion as well for ablation of both sides of the septumwall 193.

[0166] In an alternative embodiment of the clamping probe 198, as shownin FIG. 31, the outer and inner jaw portions 200, 201 may cooperate toprovide a gap 217 at and between the outer elbow portion 166 and theinner elbow portion 207. This gap 217 is formed to accommodate thetypically thicker tissue juncture 218 where the septum wall 193intersects the outer atrial wall 220. Hence, when the clamping probe 198is moved to the clamped condition, the gap 217 is formed to receive thistissue juncture 218 so that a more constant compression force may beapplied across the septum wall between the opposing jaws. This may beespecially problematic when the tissue juncture is significantly thickerthan the septum wall which, due to the disparity in thickness, may notenable the distal ends of the respective jaw portions to effectivelycontact the septum wall for transmural ablation thereof.

[0167] While FIG. 31 illustrates that the gap 217 is primarily formedthrough the offset curvature at the elbow portion 207 of inner jawportion 201, it will be understood that the outer jaw portion 200 aloneor a combination thereof may be employed to form the gap 217. Further,in some instances, the clamping probe 198 may be derived from the rightangle probe set forth above.

[0168] After completion of the above-mentioned series of elongatedlesions formed through the retractor, the right atrial appendage RAA maybe excised along the direction of solid line 221 in FIG. 3 and brokenline 222 in FIG. 19, to be described below. This excision is optionaldepending upon the particular circumstance since the risk of a fatalclot or thromboembolism is not as great as compared to left atrialappendage LAA. Should this excision be performed, the right atrialappendage RAA will, preferably, first be sutured closed along brokenline 222 using conventional thoracoscopic instruments. This closure mustbe hemostatic to prevent blood loss when the right atrial appendage isexcised. Once a hemostatic seal is attained, the appendage is excisedusing thoracoscopic scissors or an incision device.

[0169] While suturing is the preferred technique for hemostaticallysealing the right atrial chamber, the right atrial appendage may firstbe surgically closed along broken line 222 using staples. In thisprocedure, a thoracoscopic stapling device would be inserted into thethoracic cavity through the retractor passageway 67 for access to theappendage. Moreover, the right atrial appendage may be conductivelyisolated by applying a specially designed cryoprobe clamping device (notshown) formed to be placed across the base of the appendage to engagethe exterior surface thereof. This lesion will extend completely aroundthe base along the line 221, 222 in FIGS. 3 and 19 which corresponds tothe right atrial appendage excision in the prior surgical procedures.

[0170] The next series of lesions are accessed through the left atriumLA. Accordingly, a second access device 223, preferably the retractor68, placed between the ribs on the left side of the patient P, usuallyin the third or fourth intercostal space, and most preferably the thirdintercostal space as shown in FIG. 11A. Again, this percutaneouspenetration is positioned so that thoracoscopic instruments introducedthrough it may be directed toward the left atrium LA of the heart H.When additional maneuvering space is necessary, the intercostal spacebetween the ribs may be through spreading of the adjacent ribs, orportions of the ribs can be easily removed to widen the percutaneouspenetration. Further, the right lung will be re-inflated for use, whilethe left lung will be deflated to promote access while surgery is beingperformed. Other lung ventilation techniques may be employed such ashigh frequency ventilation without departing from the true spirit andnature of the present invention.

[0171] Subsequently, a pericardiotomy is performed to gain access to theleft side of the heart H utilizing thoracoscopic instruments introducedthrough the retractor 68. Using the same technique mentioned above, afifth 4-0 purse-string suture 63 is then formed in the atrial epicardiumof left atrial appendage LAA proximate a lateral midpoint thereof.Through a fifth penetration 161 formed central to the fifth purse-stringsuture 63, the orifices of the pulmonary veins can be accessed toprocure conductive isolation from the remainder of the left atrium LA.

[0172] In the preferred embodiment, the pulmonary vein isolation lesion52 is formed using a two or more step process to completely encircle andelectrically isolate the four pulmonary veins. In the preferred form, afour-step technique is employed initially commencing with the use of aC-shaped, probe 225. As best viewed in FIGS. 19A and 32, the probeincludes an elongated shaft 66 and a C-shaped ablating end 70 mounted tothe distal end of the shaft 66. The C-shaped ablating end 70 is shapedand dimensioned such that a distal end of the ablating end curves aroundand terminates in a region proximate the longitudinal axis extendingthrough the shaft. The ablating end preferably includes an arc length ofabout 120° to about 180°, and a radius of the arc between about 6.0 mmto about 25.0 mm. This equates to an ablating surface length ofpreferably about 3.0 cm to about 6.0 cm.

[0173] With the aid of a thoracoscopic grasping instrument (not shown inFIG. 19A), the distal end of probe 225 is inserted through fifthpenetration 161 to a position past the semi-circular ablating surface65. A fifth tensioning sleeve 226 may be cinched tighter in the event toprevent blood loss therefrom.

[0174] To create the first segment 227 of the pulmonary vein isolationlesion 52, the distal end of the all-purpose probe is preferablypositioned to contact the pulmonary endocardial surface 228 of the leftatrium LA about 3-10 mm superior to the right superior pulmonary veinorifice 230. Through the manipulation of the probe handle from outsidethe body, a bight portion 232 of the ablating surface 65 is positionedabout 3-10 mm outside of and partially encircling the right superior andleft superior pulmonary vein orifices 230, 231. Once aligned, theablating surface 65 of the probe is urged into ablative contact with thedesired pulmonary endocardial surface 228 to form about {fraction (1/3)}of the pulmonary vein isolation lesion 52 (i.e., the first segment 227).

[0175] Without removing the probe 225 from the fifth penetration 161,the probe 225 is rotated approximately 180° about the longitudinal axisof the probe shaft 66 to reorient the ablating surface 65 to form thesecond segment 233 of the pulmonary vein isolation lesion 52. FIG. 19Bbest illustrates that the bight portion 232 of the probe is positionedon the other side of pulmonary trunk to contact the pulmonaryendocardium about 3-10 mm just outside of and partially encircling theright inferior and left inferior pulmonary vein orifices 235, 236. Toensure segment continuity, the distal end of the probe is positioned tooverlap the distal of the first segment 227 by at least about 5 mm. Oncethe probe bight portion 232 is aligned to extend around the pulmonaryvein orifices, the ablating surface 65 thereof is urged into ablativecontact with the desired pulmonary endocardium to form the secondsegment 233 of the pulmonary vein isolation lesion 52. After ablativecontact and subsequent probe defrosting, the probe is retractedrearwardly from the fifth penetration 161 and removed from the secondretractor 68. An articulating probe (not shown) may also be employed forthis procedure which includes an ablating end capable of selectedarticulation of the ablating surface to vary the curvature thereof. Inthis probe, the articulation of the end may be manually or automaticallycontrolled through control devices located at the handle portion of theprobe. This probe may be particularly suitable for use in the formationof the pulmonary vein isolation lesion due to the anatomical accessdifficulties.

[0176] Immediately following removal of the probe 225, a right angleprobe is to be inserted through the fifth penetration 161 of the leftatrial appendage LAA, in the manner above discussed, to create a thirdsegment 237 of the pulmonary vein isolation lesion 52. The formation ofthis segment may require a different right angle probe, having a shorterlength ablating surface 65 (about 2.0 cm to about 6.0 cm) than that ofthe first right angle probe 163 utilized in the previous ablativeprocedures. As shown in FIGS. 19C, the ablating surface 65 is orientedjust outside the left superior pulmonary vein orifice 231 by at leastabout 5 mm. Again, to ensure proper segment continuity, it is importantto overlap the distal end of the ablating surface 65 with thecorresponding end of the lesion during the formation of the thirdsegment 237 of the pulmonary vein isolation lesion 52. After the probeis manually urged into contact with the desired pulmonary endocardialsurface 228, cryothermia is induced for the designated period totransmurally ablate the third segment 237 of the pulmonary veinisolation lesion 52 Subsequently, the right angle probe ablating surface65 is properly defrosted to reverse cryoadhesion and enable separationfrom the tissue.

[0177] Similar to the use of the probe 225, without removing the rightangle probe from the fifth penetration 161, the probe is rotatedapproximately 180° about the longitudinal axis of the probe shaft toposition the ablating surface 65 just outside the left inferiorpulmonary vein orifice 236 by at least about 5 mm (FIG. 19D). Again, toensure proper segment continuity, it is important to overlap both thedistal end and the elbow portion of the ablating surface 65 with thecorresponding ends of the second and third segments 233, 237 during theformation of the fourth segment 238 of the pulmonary vein isolationlesion 52. Fiberoptic visualization or the like is employed tofacilitate proper continuity between the segments and placement of theprobe. Once the probe is urged into contact with the desired left atriuminterior surface, cryothermia is induced for the designated period toablate the fourth segment of the pulmonary vein isolation lesion 52.After the right angle probe ablating surface 65 is properly defrosted,the probe is retracted rearwardly from the fifth penetration 161 andremoved from the second retractor 68.

[0178] Formation of this last segment (i.e., fourth segment 238)completes the reentrant path isolation encircling the pulmonary veins(i.e., the pulmonary vein isolation cryolesion 52). It will beappreciated, of course, that the order of the segment formation whichcollectively defines the pulmonary vein isolation lesion 52 may vary. Itis imperative, however, that there be continuity between the foursegments. If the four-step procedure is performed properly, the opposedends of the four segments should all overlap and interconnect to formone unitary ablation transmurally encircling the pulmonary trunk 108.

[0179] In accordance with the system and procedure of the presentinvention, an alternative two-step endocardial procedure may beperformed to isolate the pulmonary veins. As shown in FIGS. 20A and 33,an S-shaped end probe 240 is provided having a uniquely shaped,opened-looped ablating surface 65 formed to substantially extend aroundor encircle the pulmonary vein orifices. The S-shaped probe 240 includesan elongated shaft 66 having a substantially straight first portion 175and a C-shaped second portion 176 mounted to the distal end of the firstportion and terminating at a position proximate the longitudinal axis ofthe first portion 175 of shaft 66. Mounted to the distal end of theC-shaped second portion 176 is a C-shaped ablating end 70 which curvesback in the opposite direction such that the two C-shaped sectionscooperate to form an S-shaped end. This unique shape enables theablating surface 65 of ablating end 70 to have an arc length of betweenabout 290° to about 310°, with a radius of curvature of about 1.2 cm toabout 3.0 cm.

[0180]FIG. 33 illustrates that the C-shaped ablating end 70 is shapedand dimensioned such that a distal end of the ablating end curves aroundand terminates in a region proximate the longitudinal axis extendingthrough the shaft. Consequently, the ablating end 70, having a radius ofabout 12.0 mm to about 25.0 mm, can then extend substantially around theendocardial surface of the pulmonary vein trunk. This is accomplished byproviding the C-shaped second portion 176 having a radius of curvatureof at least bout 5 mm to about 7 mm which enables the unimpeded flow ofcryogen through the delivery tube of the shaft 66. The elimination orsubstantial reduction of this C-shaped second portion 176 positionedjust before the C-shaped ablating end 70 would create such an acuteangle that the flow of cryogen about that angle may be impeded.

[0181] Using thoracoscopic grasping instruments, the distal end of thisprobe is carefully inserted through the fifth purse-string suturepenetration 161. Due in part to the unique near-circular shape of theablating surface 65, initial insertion through the fifth penetration maybe one of the most difficult and problematic portions of this procedure.

[0182] As shown in FIG. 20A, after the ablating surface 65 of the probe240 is successfully inserted through the fifth penetration 161, thelooped ablating surface 65 is aligned and positioned to substantiallyencircle the pulmonary vein orifices. Through manipulation of the probehandle from outside the thoracic cavity, the probe ablating surface 65is urged into contact with the pulmonary endocardial surface 228 about3-10 mm just outside of the pulmonary vein orifices. Upon properalignment and ablative contact with the epicardial tissue, a firstsegment 241 of this technique is formed (FIG. 20B) which preferablyconstitutes at least about {fraction (3/4)} of the pulmonary veinisolation lesion. After proper defrosting, the loop probe is removedfrom the fifth penetration and withdrawn through the retractor.

[0183] To complete this alternative two-step procedure, an alternativeright angle probe, above-mentioned, is inserted through the fifthpenetration 161 upon removal of the S-shaped probe 240. FIG. 20Billustrates that both the distal end and the elbow portion of the probeablating surface 65 are aligned to overlap the corresponding ends of thefirst segment 241 during the formation of a second segment 242 of thepulmonary vein isolation lesion 52. This ensures continuity between thetwo connecting segments.

[0184] It will be understood that other shape probes may be employed toisolate the pulmonary trunk. The particular customized shape may dependupon the individual anatomical differences of the patient, especiallysince atrial fibrillation patients often have enlarged or distortedatria.

[0185] It may be beneficial to access and perform portions of either thefour-step procedure or the two-step procedure through the right side ofthe thoracic cavity. In these instances, access may be achieved throughthe first access device 68 and the fourth penetration 160 of the fourthpurse-string suture 62. Moreover, due to the arduous nature of theformation, placement and alignment between these segments composing theendocardial pulmonary vein isolation lesion in either the two or foursegment procedure, it may be necessary to ablate an epicardial lesion243 in the epicardial surface 168 encircling the pulmonary trunk 108 toensure effective transmural tissue ablation for pulmonary veinisolation. Referring to FIGS. 21 and 33, an epicardial pulmonary veinloop probe 240, substantially similar to the probe employed in theprocedure of FIG. 20A, is provided for introduction through thepassageway of the retractor. This probe instrument includes anopen-looped ablating surface 65 defining an opening 245 (FIG. 33) formedfor passage of the pulmonary trunk 108 therethrough. Using thoracoscopicgrasping instruments, the probe 240 is situated under the pulmonaryveins wherein the pulmonary trunk 108 is urged through the opening 245in the looped ablating surface. Once the ablating surface 65 is alignedto contact a pulmonary epicardial surface 168 of the pulmonary trunk 108at a position opposite the epicardial pulmonary vein isolation lesion52, cryogenic liquid is introduced into the boiler chamber of the loopprobe 240 for cryogenic cooling of the ablating surface 65. Aftercontact for the designated period (2-4 minutes) and proper probedefrosting, the loop probe is separated from the pulmonary trunk andretracted rearwardly out of the retractor 68.

[0186] Alternatively, this pulmonary epicardial surface isolation may beperformed from the right side of the thoracic cavity through the firstaccess device 68 (not shown). In this alternative method, theopen-looped ablating surface 65 of the loop probe 240 is positionedbehind the superior vena cava 111, across the anterior surface of theright pulmonary veins, and underneath the inferior vena cava 103. Onceproperly positioned, the epicardial surface 168 of the pulmonary trunk108 can be ablated.

[0187] Turning now to FIG. 22, formation of the left atrial anteromediallesion 246 will be described in detail. This lesion 246 is relativelyshort extending only about 5-7 mm from the anteromedial portion of theleft atrial appendage LAA to the pulmonary vein isolation lesion 52proximate a central portion between the left superior and inferiorpulmonary vein orifices 231, 236. Due to the position of this lesion andthe flexible nature of the appendage tissue, any one of a number ofprobes already mentioned, such as the probes illustrated in FIG. 32, theright angle probe (FIG. 24) or the pulmonary vein to mitral valve probe(FIG. 34), can be employed for this task. Typically, the probe device247 of FIG. 34 is employed which includes an elongated shaft 66 having afirst elbow portion 166 positioned between a relatively straight firstportion 175 and a generally straight second portion 176. The first elbowportion has an arc length of about 45° to about 65° and a radius ofcurvature of about 3.2 cm to about 5.7 cm. Further, a second elbowportion 177 is positioned between the second portion 176 and theablating end 70, angling the ablating end back toward the longitudinalaxis of the first portion 175 of the elongated shaft 66. The ablatingend 70 preferably includes the second elbow portion 177, having an arclength of about 80° to about 100°, and a radius of curvature of about6.0 mm to about 1.9 mm. This translates to an ablating surface of about2.0 cm to about 6.0 cm in length.

[0188] One of the above-mentioned probes will be introduced through thesecond retractor 68 where the distal end of the probe will be insertedthrough the same fifth penetration 161 central to the fifth purse-stringsuture 63. Once the selected probe 247, as shown in FIG. 22, is properlyaligned, the ablating surface 65 is urged into contact with the atrialendocardial surface of the left atrial appendage LAA for localizedablation. Subsequently, the left atrial anteromedial lesion 246 will beformed.

[0189] Since the left atrial wall at the anteromedial portion thereof isexceedingly thin, this transmural ablation could be performed fromoutside the heart H. Hence, upon contact of the ablating surface of aselected probe (not shown) with the atrial epicardial surface of theleft atrial appendage LAA, localized, transmural cryothermia may beapplied externally/epicardially to form this left atrial anteromediallesion 246.

[0190] The last lesion to be performed through the fifth penetration 161is the posterior vertical left atrial lesion 248, also known as thecoronary sinus lesion (FIG. 23), extending from the pulmonary veinisolation lesion 52 to the annulus 250 of the mitral valve MV. Thislesion may be critical since improper ablation may enable atrialconduction to continue in either direction beneath the pulmonary veins.This may result in a long macro-reentrant circuit that propagates aroundthe posterior-inferior left atrium, the atrial septum, theanterior-superior left atrium, the lateral wall of the left atriumbeneath the excised left atrial appendage, and back to the posteriorinferior left atrium.

[0191] Therefore, it is imperative that the coronary sinus be ablatedcircumferentially and transmurally in the exact plane of the atriotomyor lesion. Proper transmural and circumferential ablation near thecoronary sinus effectively eliminates the need for dividing all atrialmyocardial fibers traversing the fat pad of the underlyingatrioventricular groove.

[0192] In the preferred embodiment, a modified probe 251 (FIG. 35) isemployed to ablate this critical coronary sinus lesion 248. This probe251 includes an elongated shaft 66 having a first elbow portion 166positioned between a generally straight first portion 175 and agenerally straight second portion 176. The first elbow portion has anarc length of about 30° to about 50° and a radius of curvature of about1.2 cm to about 3.0 cm. Mounted at the distal end of the second portion176 is the ablating end which is substantially similar in shape to theablating end of the probe of FIG. 32. The ablating end 70 curves backtoward the longitudinal axis of the first portion 175 of the elongatedshaft 66.

[0193] Again, this interior region of the heart H is accessed throughthe fifth penetration 161, via the second access device 223. The distalend of the probe 251, is positioned through the penetration in the samemanner as previous ablations. The unique curvature of this probe 251enables manipulation of the ablating surface 65 from outside thethoracic cavity into proper alignment. FIG. 23 best illustrates thatablating surface 65 is moved into contact with the endocardial surfaceof the left atrial wall atrium for localized ablation extending from thepulmonary vein isolation lesion 52 to the mitral valve annulus 250.Particular care, as mentioned above, is taken to assure that this lesionextends through the coronary sinus for circumferential electricalisolation thereof. After contact for the designated period of 2-4minutes, the ablating surface 65 of the probe is properly defrosting andthe probe 251 is retracted rearwardly from the fifth penetration 161 forremoval from the retractor. Subsequently, the fifth penetration 161 isfurther cinched to prevent blood lose through the fifth purse-stringsuture 63.

[0194] Due to the criticality of the circumferential ablation of thecoronary sinus during formation of the pulmonary vein to mitral valveannulus lesion 248, an epicardial ablation may be performed on a portionof the outside heart wall opposite the endocardial ablation of thecoronary sinus. Thus, the placement of this additional lesion (notshown) must be in the same plane as the coronary sinus lesion 248 (i.e.,to the mitral valve annulus lesion) to assure circumferential ablationof the coronary sinus. This is performed by introducing a standard probethrough the retractor 68, and strategically contacting the epicardialsurface at the desired location opposite the coronary sinus lesion.

[0195] Upon completion of the above-mentioned series of elongatedlesions, the left atrial appendage LAA is excised along the direction ofbroken line 252 in FIG. 23, similar to that of the prior procedures.This excision is considered more imperative than the excision of theright atrial appendage RAA since the threat of thromboembolism orclotting would more likely be fatal, induce strokes or cause otherpermanent damage. In the preferred form, this excision is performed inthe same manner as the excision of the right atrial appendage (i.e.,through suturing or stapling. After hemostatic closure is attained, theleft atrial appendage LAA is excised using thoracoscopic scissors or anincision device. This left appendagectomy will extend completely aroundthe base of the left atrial appendage along the solid line 252 in FIG. 3or the broken line 253 in FIG. 23, which corresponds to the left atrialappendage excision in prior procedures.

[0196] Alternatively, the probes may be formed and dimensioned forcontact with the epicardial surface 168 of the heart H. In theseinstances, no purse-string suture may be necessary for elongatedtransmural ablation. As an example, as best viewed in FIG. 36, aright-angle clamp type probe 255 is provided having an outer clampingportion 256 coupled to and formed to cooperate with a right angle probeor inner clamping portion 257 for transmural ablation of the heart wallthrough contact with epicardial surface 168 of the heart H. In thisembodiment, an outer jaw portion 258 of outer clamping portion 256 isrelatively thin (about 0.5 mm to about 2.0 mm in diameter) andpreferably needle shaped to facilitate piercing of the heart wall atpuncture 260. At the end of the needle-shaped outer clamping portion 256is a pointed end 261 which enables piercing of the heart wall withoutrequiring an initial incision and subsequent purse-string suture toprevent blood loss through the puncture 260.

[0197] Similar to clamping probe 198, when properly positioned, theouter and inner jaw portions 258, 262 of inner clamping portion 257 aremoved inwardly in the direction of arrows 216, 216′ (the outer jawportion 258 contacting endocardial surface 228, and the inner jawportion 262 contacting epicardial surface 168) to clamp the heart walltherebetween. FIG. 36 illustrates that inner jaw portion 262 includesablation end 70 having ablation surface 65 which contacts epicardialsurface 168 for ablation. Upon withdrawal of the needle-shaped outer jawportion 258 from the heart wall, the puncture 260 may be closed througha single suture (not shown).

[0198] In these embodiments, an alignment device 263 is provided whichcooperates between the outer and inner clamping portions 256, 257 foroperating alignment between the outer jaw portion 258 and the inner jawportion 262. This alignment device may be provided by any conventionalalignment mechanism such as those alignment devices employed in theclamping probe 198.

[0199] To ensure transmural ablation, the needle-shaped outer jawportion 258 may incorporate a temperature sensor 265 (FIG. 36) embeddedin or positioned on the outer jaw portion to measure the temperature ofthe endocardial surface. Measurement of the proper surface temperaturewill better ensure transmural ablation. These temperature sensors may beprovided by a variety of conventional temperature sensors.

[0200] Referring to FIGS. 37-40, another probe 280 is shown. A cryogendelivery tube 282 is positioned within an outer tube 284. A tip 286seals an end of the outer tube 284. The delivery tube 282 is coupled tothe source of cryogen (not shown) for delivering the cryogen to a boilerchamber 288. The cryogen is exhausted from the boiler chamber 288through the annular area between the delivery tube 282 and outer tube284. The delivery tube 282 has an end cap 290 which receives first andsecond tubes 292, 294 for delivery of cryogen to the boiler chamber 288from the delivery tube 282. The first tube 292 has an exhaust port 296which extends further into the boiler chamber 288 than an exhaust port298 of the second tube 294 so that the cryogen is distributed throughoutthe boiler chamber 288. Although FIG. 38 depicts only the first andsecond outlet tubes 292, 294, any number of tubes may be provided.

[0201] Ablating surface 300 of the outer tube 284 is preferably made ofa highly thermally conductive material such as copper. Referring to theend view of FIG. 40, the ablating surface 300 preferably has a ribbedinner surface 302 for enhanced thermal conduction between the boilerchamber 288 and the ablating surface 300. The probe 280 may take any ofthe configurations described herein.

[0202] Referring to FIGS. 41 and 42, another probe 306 is shown whichhas a device for adjusting the delivery rate of cryogen. The deliverytube 308 includes an inner tube 310 and an outer tube 312. The inner andouter tubes 310, 312 have holes 314, 316 therein through which thecryogen is delivered to boiler chamber 318. The outer tube 312 isslidable relative to the inner tube 310 and can be locked relative tothe inner tube 310 at a number of discrete positions where the holes 314in the inner tube 310 are aligned with the holes 316 in the outer tube312. The holes 314 in the inner tube 310 are larger than holes 316 inthe outer tube 312 so that when the outer tube 312 is in the position ofFIG. 41 a larger amount of cyrogen is delivered than when the outer tube312 is in the position of FIG. 42. Thus, the amount of cyrogendelivered, and therefore the rate of ablation and temperature of theprobe 306, can be changed by moving the outer tube 312 relative to theinner tube 310. The delivery tube 308 may be used in the mannerdescribed above with any of the probe configurations described herein.

[0203] Referring to FIGS. 43 and 44, still another probe 318 is shownwhich includes suction ports 320 for ensuring intimate contact betweenthe ablating surface 322 and the tissue. The suction ports 320 arecoupled to a longitudinal channel 324 which is coupled to a vacuumsource for applying suction. A cryogen delivery tube 326 deliverscryogen to boiler chamber 328 in the manner described herein.

[0204] Referring to FIGS. 45-47, a probe 330 having a malleable shaft332 is shown. A malleable metal rod 334 is coextruded with a polymer 336to form the shaft 332. A tip 338 having a boiler chamber 340 is attachedto the shaft 332. The rod 334 permits the user to shape the shaft 332 asnecessary so that the tip 338 can reach the tissue to be ablated. Thetip 338 has fittings 342 which are received in a cryogen exhaust path344 and a cryogen delivery path 346 in the shaft 332. The rod 334 ispreferably made of stainless steel and the polymer 336 is preferablypolyurethane. The tip 338 may be made of a suitable thermally conductivematerial such as copper. Cryogen is delivered through ports 348 in adelivery tube 350 and is expanded in the boiler chamber 340. The cryogenis then withdrawn through the exhaust path 344.

[0205] Finally, as set forth in the parent application incorporatedherein by reference, access devices may be placed in the heart walls toenable the passage of the probes through the wells of the accessdevices.

[0206] While the present invention has been primarily directed towardablation from the endocardial surfaces of the atria, it will beunderstood that many lesions or portions of the lesions may be createdthrough ablation of the endocardial surfaces of the atria employing thepresent probes. While the specific embodiments of the inventiondescribed herein will refer to a closed-chest surgical procedure andsystem for the treatment of medically refractory atrial fibrillation, itis understood that the invention will be useful in ablation of othertissue structures, including surgical treatment of Wolfe-Parkinson-White(WPW) Syndrome, ventricular fibrillation, congestive heart failure andother procedures in which interventional devices are introduced into theinterior of the heart, coronary arteries, or great vessels. The presentinvention facilitates the performance of such procedures throughpercutaneous penetrations within intercostal spaces, eliminating theneed for a median sternotomy or other form of gross thoracotomy.However, as will be apparent although not preferred, the system andprocedure of the present invention could be performed in an open-chestsurgical procedure as well.

What is claimed is:
 1. A method for treatment of a heart comprising thesteps of: forming a penetration through a muscular wall of the heartinto an interior chamber thereof; positioning a distal end of anelongated ablating device having an elongated ablating surface throughthe penetration; and contacting the elongated ablating surface of theablating device with a first selected portion of an interior surface ofthe muscular wall for transmural ablation thereof.
 2. The method ofclaim 1 further including the step of: manipulating the device throughsaid penetration to strategically contact the elongated ablating surfacewith a second selected portion of the interior surface of the muscularwall for transmural ablation thereof.
 3. The method of claim 1 furtherincluding the steps of: repeating the forming, positioning andcontacting steps to form a plurality of strategically positionedlesions.
 4. The method of claim 3 wherein, the lesions are formed tocreate a predetermined conduction pathway in the muscular wall.
 5. Themethod of claim 1 wherein, the interior chamber is selected from a rightatrium and a left atrium.
 6. The method of claim 1 wherein, the ablatingsurface is disposed at an angle of at most about 90 degrees relative tothe longitudinal axis of the shaft.
 7. The method of claim 1 furtherincluding the step of: forming a hemostatic seal between the device andthe penetration to inhibit blood loss through the penetration.
 8. Themethod of claim 7 wherein: the seal forming step is carried out byplacing a purse-string suture in the muscular wall of the heart aroundthe penetration.
 9. The method of claim 1 wherein, the heart remainsbeating throughout the forming, positioning, and contacting steps. 10.The method of claim 1 further including the step of: arresting thepatient's heart.
 11. The method of claim 10 wherein, the arresting stepis performed by endovascularly occluding the ascending aorta.
 12. Themethod of claim 1 wherein, the ablating device is a radiofrequencyprobe.
 13. The method of claim 1 wherein, the ablating device is a laserprobe.
 14. The method of claim 1 wherein, the ablating device is amicrowave probe.
 15. The method of claim 1 wherein, the ablating deviceis a fluid delivery probe.
 16. A method for ablating medicallyrefractory atrial fibrillation of the heart comprising the steps of:forming a penetration through a wall of the heart; positioning a distalend of an ablating device having an elongated ablating surface throughthe penetration; forming a hemostatic seal between the ablating deviceand the penetration to inhibit blood loss therethrough; contacting theelongated ablating surface with at least one selected portion of aninterior surface of the heart for transmural ablation thereof to form atleast one elongated transmural lesion.
 17. The method of claim 16,further comprising the step of: repeating the forming, positioning, andcontacting steps to form a plurality of lesions, the plurality oflesions cooperating to generally form a conduction pathway between thesinoatrial node and the atrioventricular node.
 18. The method of claim16 wherein, the interior chamber is selected from a right atrium and aleft atrium.
 19. The method of claim 16, wherein at least one hemostaticseal is formed by tightening a purse-string suture in the heart wallaround the respective penetration.
 20. A system for transmurallyablating heart tissue in a body cavity surrounded by a chest wallcomprising: a probe having an elongated shaft positionable through thechest wall and into a penetration extending through a wall of thepatient's heart, said shaft having a substantially elongated ablatingsurface proximate a distal end thereof for manipulative contact with atleast one selected surface of the wall of the heart for transmuralablation thereof; and a sealing device fixable to the heart tissuearound said penetration for forming a hemostatic seal around the shaftand the transmural penetration to inhibit blood loss therebetween.